Maximize Availability with Oracle Database 12c

Maximize Availability with Oracle Database 12c
Maximize Availability with Oracle Database 12c
Table of Contents
The High Availability Challenge
Oracle Database High Availability
Innovation in Oracle Database 12c
Oracle Database HA Design Principles
Oracle Maximum Availability Architecture
Addressing Unplanned Downtime
Server HA: Oracle Real Application Clusters
Transparent Failover: Application Continuity
Storage: Automatic Storage Management (ASM)
Data Availability and Corruption Protection
Backup and Recovery – Oracle Recovery Manager
Backup to Tape – Oracle Secure Backup (OSB)
Zero Data Loss Recovery Appliance, Real-Time Data Protection
Recovery from Logical Corruption: Oracle Flashback Technology
Real-time Data Protection and Availability – Oracle Data Guard
High Availability with Zero Data Loss across Any Distance: Active Data Guard
Active-Active HA: GoldenGate
Complete Site Failover: Oracle Site Guard
Addressing Planned Downtime
Online System Reconfiguration
Online Data and Application Change
Online Application Upgrades: Edition-Based Redefinition
Hot Patching
Rolling Patch Upgrades using Oracle RAC
Data Guard Standby-First Patch Assurance
Database Rolling Upgrades using Data Guard
Database Rolling Upgrades using Active Data Guard
Platform Migration, Systems Maintenance, Data Center Moves
Zero Downtime Maintenance using Oracle GoldenGate
Managing Oracle Database High Availability Solutions
Global Data Services
Appendix: New High Availability Features in Oracle Database 12c
Enterprises use Information Technology (IT) to gain competitive advantages, reduce operating
costs, enhance communication with customers, and increase management insight into their
business. Thus enterprises are becoming increasingly dependent on their IT infrastructure and its
continuous availability. Application downtime and data unavailability directly translate into lost
productivity and revenue, dissatisfied customers, and damage to corporate reputation.
A basic approach to building a High Availability (HA) infrastructure is to deploy redundant and often
idle hardware and software resources supplied by disparate vendors. This approach is often
expensive, yet falls short of service level expectations due to loose integration of components,
technological limitations, and administrative complexity. In contrast, Oracle provides customers with
comprehensive and integrated HA technologies to reduce cost, maximize their return on investment
through productive use of all HA resources, and improve quality of service to users.
In this paper, we examine the types of outages that affect IT infrastructures, and present Oracle
Database technologies that comprehensively address those outages. These technologies,
integrated into Oracle’s Maximum Availability Architecture (MAA), reduce or avoid unplanned
downtime, enable rapid recovery from failures, and minimize planned downtimes.
We introduce new Oracle Database 12c features, including Application Continuity, Global Data
Services, and Active Data Guard Far Sync, which improve application recovery, support global
database services, and extend zero-data-loss protection to a global scale, respectively. We
describe enhancements to Oracle Database 12c performance, functionality, and ease-of-use to
existing HA features including Real Application Clusters, Automatic Storage Management,
Recovery Manager, Data Guard and Active Data Guard, Oracle Secure Backup, and Edition-Based
Redefinition. We also introduce innovative new capabilities that revolutionize data protection and
recovery with the Zero Data Loss Recovery Appliance.
The High Availability Challenge
Designing, implementing, and managing a high availability (HA) architecture that achieves all business objectives
under real-world constraints is quite difficult. Many technologies and services from different suppliers offer to
protect your business from data loss and downtime - who can you trust?
Oracle believes that HA encompasses a number of important aspects in addition to the main goal of preventing
downtime. Key dimensions of a comprehensive HA architecture includes:
» Data availability: ensuring access to data to prevent business interruption.
» Data protection: preventing data loss that compromises the viability of the business.
» Performance: delivering adequate response time for efficient business operations.
» Cost: reducing deployment, management and support costs to conserve corporate resources.
» Risk: consistently achieving required service levels over a long period of time as the business evolves with no
costly surprises or disappointments.
Successful HA begins with understanding the service levels required by the business along each of these
dimensions. This guides important decisions on technology and determines the appropriate level of investment in
HA architecture.
Successful HA solutions achieve service level objectives along each of the above dimensions. They must be
flexible because different applications, business functions and groups of users have different service level
requirements. They must also be able to quickly adapt because no solution is permanent - requirements evolve
as business conditions change.
Oracle Database High Availability
Oracle has been hard at work for over three decades helping IT solve HA challenges by designing
comprehensive HA capabilities integrated into the database. This innovation results in HA solutions that give true
competitive advantages to enterprises, by helping them achieve service level objectives for high availability in the
most cost-effective manner.
Oracle Database HA capabilities address the full range of planned and unplanned outages. Oracle builds and
delivers database-aware HA capabilities that are deeply integrated with core internal features of the database.
This results in cost effective solutions that reduce business risk and achieve unique levels of data protection,
availability, performance and return on investment. Oracle Database HA capabilities are flexible, enabling you to
choose the appropriate level of HA, and are adaptable, to efficiently support your business objectives today and
in the future.
Innovation in Oracle Database 12c
Oracle Multitenant, a new option for Oracle Database 12c, delivers groundbreaking technology for database
consolidation and cloud computing. The Multitenant architecture drives down IT costs by enabling a true
‘manage-as-one’ architecture for consolidation and virtualization of the database tier. The Multitenant architecture
also makes extreme high availability a fundamental requirement when database consolidation is applied to
business-critical applications. By definition, database consolidation is an exercise of ‘putting all eggs in one
basket.’ The more successful you are at driving down cost through consolidation, the more eggs are in a single
basket, and the greater is the operational and financial impact to the business should an outage occur.
New high availability (HA) capabilities in Oracle Database 12c are designed to provide the extreme level of
availability required for consolidating databases onto Private Clouds. This includes support for multitenant
architecture across all Oracle HA features, new levels of redundancy, transparent failover of in-flight transactions,
zero-data loss disaster protection at any geographic distance. The Oracle Multitenant architecture represents the
next-generation in database technology, and long-standing and time-proven Oracle HA design principles are
ready from day one to provide the extreme availability required by consolidated environments.
Oracle Database HA Design Principles
Oracle Database HA relies on a set of tightly integrated HA features built within the database kernel. Oracle’s
vision for High Availability is guided by three principles, described next.
Leverage Oracle database internals for maximum data protection
Knowledge and control of its internal algorithms and data structures, including database block structure and redo
format, enables Oracle to build intelligent, unique-to-Oracle data protection. For instance, because it can detect
corruption in a database at the earliest opportunity, Oracle Data Guard prevents propagation of physical
corruption, logical intra-block corruption, and logical corruptions caused by lost-writes. Active Data Guard goes a
step further, automatically repairing physical on-disk corruption that can occur at either the primary or standby
database transparent to the user.
Similarly, Recovery Manager (RMAN) performs Oracle aware physical and logical block validation ensuring valid
backups. RMAN enables a backup once, incremental forever strategy that only backs up changed blocks,
providing implicit source-side deduplication that is more efficient than an external de-duplication appliance.
RMAN also does fine-grained, efficient recovery of individual blocks instead of entire data files. Another uniqueto-Oracle example of data protection is the ability of Flashback technologies to undo database changes at a level
of granularity appropriate to the scope of the error, be it the entire database, or a table, or an individual
transaction, without requiring a full database restore.
Deliver application-integrated high availability
Providing HA and data protection using cold failover clusters or at the raw bits level as done by storage-centric
solutions is inadequate for comprehensive protection and fast recovery. Oracle Real Application Clusters (Oracle
RAC) enables a single Oracle Database to run on a cluster of database servers in an active-active configuration.
Performance is easy to scale out through online-provisioning of additional servers – users are active on all
servers, and all servers share access to the same Oracle Database. HA is maintained during unplanned outages
and planned maintenance by transitioning users on the server that is out of service to other servers in the Oracle
RAC cluster that continue to function.
Outages ultimately impact the availability of an application and, unlike storage-centric solutions, Oracle HA
technologies are designed to operate at the business object level – e.g., repairing tables or recovering specific
transactions. Oracle solutions enable granular recovery and thus very efficient, with no disruption to the
availability of applications using unaffected portions of the database. Oracle also allows making structural
changes to a table while others are accessing and updating it, via the Online Redefinition feature. Application
Continuity, a new capability in Oracle Database 12c, masks many outages from end users and applications by
replaying the session after a server or site failover has occurred, transparent to the application.
Oracle HA solutions go beyond unplanned outages. All types of database maintenance can be performed either
online or in rolling fashion for minimal or zero downtime. Data Guard standby systems are easily dual-purposed
as test systems, reducing risk by ensuring all changes are fully tested on an exact copy of the production
database before they are applied to the production environment.
Provide an integrated, automated, and open architecture with high return on investment
HA features built into the Oracle Database require no separate integration or installs. Upgrades to new versions
are greatly simplified, eliminating the painful and time-consuming process of release certification across multiple
vendors' technologies. Also, all the features can be managed via the unified Oracle Enterprise Manager Cloud
Control management interface. Oracle builds automation into every step, preventing common mistakes typical in
manual configurations. For example, customers can easily choose to automatically fail over to a standby
database if the production database becomes offline; to automatically remove and archive backups for effective
space management; and to automatically repair physical block corruptions.
Oracle HA solutions are inherently active – avoiding idle components that only function when a failure occurs. All
Oracle RAC nodes are active, Data Guard standby systems support read-only applications, data extracts, and
fast incremental backups, and Oracle GoldenGate supports read-write workloads with conflict resolution
distributed across replicated copies of an Oracle Database in an update-anywhere architecture. Oracle’s active
HA architecture provides high ROI and the same time it minimizes risk of failure. There is never a question of if it
will start and how long it will take after a failure occurs to resume service: all Oracle HA components are already
started, already performing useful work, enabling continuous user validation that they are ready for prime-time.
Oracle Maximum Availability Architecture
Oracle Maximum Availability Architecture (MAA) is a set of best practice blueprints for the integrated use of
Oracle High Availability (HA) technologies (see Figure 1).
Figure 1: Oracle’s High Availability Technologies and the Oracle Maximum Availability Architecture
MAA best practices are created and maintained by a team of Oracle developers that continually validate the
integrated use of Oracle Database HA features. Real-world customer experience is also integrated into the
validation performed by the MAA team, spreading lessons learned to other customers.
MAA includes best practices for critical infrastructure components including servers, storage, and network,
combined with configuration and operational best practices for the Oracle HA capabilities deployed on it. MAA
resources ( are continually updated and extended.
Given that all applications do not have the same HA and data protection requirements, MAA best practices
describe standard architectures designed to achieve different service level objectives. Details are provided in,
Oracle MAA Reference Architectures – The Foundation for Database as a Service. 1
The remainder of this document examines HA capabilities for Oracle Database 12c in greater depth
Addressing Unplanned Downtime
Hardware faults, which cause server failure, are essentially unpredictable, and result in application downtime
when they eventually occur. Likewise, a range of data availability failures, including storage corruption, site
outage and human error, also cause unplanned downtime. In this section we discuss how Oracle’s HA solutions
address these fundamental categories of failures in order to prevent and mitigate unplanned downtime.
Server HA: Oracle Real Application Clusters
Server availability is related to ensuring uninterrupted access to database services despite the unexpected failure
of one or more machines hosting the database server, which could happen due to hardware or software fault.
Oracle Real Application Clusters (RAC) can provide the most effective protection against such failures.
Oracle Real Application Clusters (RAC) is Oracle’s premier shared everything database clustering technology.
Oracle Database with the RAC option enables multiple database instances to run on different servers in the
cluster against a shared set of data files that comprise a database. The database spans multiple hardware
systems and yet appears as a single unified database to the application.
The Oracle RAC architecture extends availability and scalability benefits to all applications, specifically:
» Fault tolerance within the server pool, especially for computer failures. Since the nodes run independently, the
failure of one or more does not affect other nodes. This architecture also allows a group of nodes to be
transparently put online or taken offline, while the rest of the system continues to provide database services.
» Flexibility and cost effectiveness in capacity planning, so that a system can scale to any desired capacity as
business needs change. Oracle RAC gives users the flexibility to add nodes to the system as capacity needs
increase, reducing costs by avoiding the more expensive and disruptive upgrade path of replacing an existing
monolithic system with a larger one. Oracle RAC supports enables near-linear scaling without any changes to
your application.
Application Continuity, a new capability with Oracle Database 12c, protects applications from database session
failures due to instance, server, storage, network or any other related component. Application Continuity re-plays
affected “in-flight” requests so that the failure of a RAC node appears to the application as a slightly delayed
execution. See Application Continuity, below, for more details.
Oracle RAC also supports the new multitenant architecture, and in addition to providing server HA, Oracle RAC
software stack 2 is also the ideal shared infrastructure for database consolidation.
For more information see Real Application Clusters resources on OTN (
Transparent Failover: Application Continuity
It is complex for application development to mask database session outages; as a result, errors and timeouts are
often exposed to end users leading to frustration and lost productivity. Oracle Database 12c introduces
Application Continuity, a new capability that masks outages by recovering the database session following
unplanned outages. Application Continuity performs this recovery beneath the application so that the outage
appears to the application as a slightly delayed execution.
Storage: Automatic Storage Management (ASM)
Oracle Automatic Storage Management (ASM) is the underlying (clustered) volume manager technology used by
the Oracle database and Oracle ASM Cluster File System (ACFS) that enables storing and managing any type of
data on shared storage. Through its low cost, ease of administration and high performance, ASM is the storage
technology of choice for Oracle databases.
For performance and high availability, ASM stripes and mirrors everything. Intelligent mirroring capabilities allow
administrators to define 2- or 3-way mirrors to protect data. When a read operation identifies that a corrupt block
exists on disk, ASM automatically relocates the valid block from the mirrored copy to an uncorrupted portion of
the disk. Administrators can also use the ASMCMD utility to manually relocate specific blocks. When disk failures
occur, system downtime is avoided by using the data available on the mirrored disks. If the failed disk is
permanently removed from ASM, the underlying data is striped or rebalanced across the remaining disks for
continued high performance.
Flex ASM, a new capability of Oracle Database 12c, increases database (instance) availability by enabling internode storage failover and reducing ASM-related resource consumption by up to 60%. Flex ASM facilitates cluster
based database consolidation, as it ensures that database instances running on a particular server will continue
to operate, should the ASM instance on for that server fail.
ASM disk scrubbing, a new capability of Oracle Database 12c, checks for logical corruptions and repairs them
automatically, in both normal and high-redundancy disk groups. This complements the health checks that RMAN
performs during backup and recovery.
Data Availability and Corruption Protection
Data availability is about avoiding and mitigating data failures: the loss, damage, or corruption of business-critical
data. Data failures are due to one or a combination of causes: storage subsystem failure, site failure, human
error, and corruption. Their multifaceted causes often make data failures difficult to identify and diagnose. This
and subsequent sections examine the HA technologies included in the Oracle Database that help diagnose,
prevent, mitigate, and recover from data failure.
2 Oracle Grid Infrastructure including Oracle ASM / ACFS and Oracle Clusterware, and the Oracle database with the Oracle Real Application
Clusters option, constitute the Oracle Database RAC software stack.
Human Error Protection
Human errors are a leading cause of downtime, hence good risk management must include measures to prevent
and remediate human error. For example, an incorrect WHERE clause may cause UPDATE to affect many more
rows than intended. Oracle Database 12c provides a set of powerful capabilities that help administrators prevent,
diagnose and recover from such errors. It also includes features for end-users to directly recover from problems,
speeding recovery of lost and damaged data.
A good way to prevent costly human errors is to restrict users’ access scope to just data and services they need.
The Oracle Database provides security tools to flexibly control user access by authenticating users and allowing
administrators to grant users only those privileges required to perform their duties.
Previously, a backup administrator, for example, would be granted broad SYSDBA privileges, with the
consequent security exposure. New privileges available with Oracle Database 12c include SYSDG and
SYSBACKUP to support separation of duties and finer scope definition for database administration. SYSDG is
for Data Guard activities such as configuration, monitoring, and effecting role change. SYSBACKUP is for
Recovery Manager (RMAN) activities such as backing up or restoring a database.
We discuss in other sections below Backup and Flashback technologies to recover from human errors.
Protection from Physical Data Corruption
Physical data corruption is created by faults in any of the components of the Input/Output (I/O) stack. When
Oracle issues a write, this database I/O operation is passed to the operating system’s code. The write goes
through the I/O stack: from file system to volume manager to device driver to Host-Bus Adapter to the storage
controller to the NVRAM cache and finally to the disk drive where the data are written. Hardware failures or bugs
in any of these components can result in invalid or corrupt data being written to disk. This corruption could
damage internal Oracle control information or application/user data – either of which can be catastrophic to the
functioning of the database. We discuss Oracle’s comprehensive set of solutions to protect data from corruption
in the next pages.
Detect and Prevent Physical and Logical Intra-Block Corruption
For comprehensive corruption protection Oracle MAA recommends deploying Data Guard combined with
appropriate parameter settings that enable key corruption checks, including block header checks, full-block
checksums, and lost-write verification (physical and logical block checking). Active Data Guard also provides
automatic repair of physical block corruption detected on a primary database using a good copy from the active
standby, and vice versa. These settings will affect performance and therefore need to be tested before
introducing them to production. See My Oracle Support Note 1302539.1 for more detail on each parameter. 3 See
the MAA whitepaper, Preventing, Detecting, and Repairing Block Corruptions for a complete discussion of this
topic. 4
Backup and Recovery – Oracle Recovery Manager
In addition to prevention and recovery technologies, every IT organization must implement a complete data
backup procedure to respond to multiple failure scenarios. Oracle provides best-of-breed, Oracle-aware tools to
3 MOS Note 1302539.1 explains the protection/performance tradeoffs of these parameters.
efficiently backup and restore data, and to recover data up to the time just before a failure occurred. Oracle
supports backups to disk, to tape, and to cloud storage. This wide range of backup options allows users to
deploy the best solution for their particular environment. The following sections discuss Oracle’s disk, tape, and
cloud backup technologies, and the Data Recovery Advisor.
Oracle Recovery Manager (RMAN)
Recovery Manager (RMAN) manages database backup, restore, and recovery processes. RMAN maintains
configurable backup and recovery policies and keeps historical records of all database backup and recovery
activities. Large databases can include hundreds of files, making backup very challenging without an Oracleaware solution. Missing even one critical file can render the entire database backup useless, and incomplete
backups may go undetected until needed in an emergency. RMAN ensures that all files required to successfully
restore and recover a database are included in database backups. During backup and restore, RMAN validates
all data to ensure that corrupt blocks are not propagated. If corrupt blocks are found during a restore operation,
RMAN automatically relies on file(s) from a previous backup as necessary for a successful recovery.
RMAN offers a choice of compression levels: BASIC is included in the Oracle Database Enterprise Edition while
LOW, MEDIUM and HIGH levels are available as part of the Oracle Advanced Compression Option (ACO). The
compression ratio and CPU usage vary from highest to lowest in the following order: HIGH, BASIC, MEDIUM
and LOW. Therefore, the HIGH compression level will achieve the best compression ratio while also requiring the
most CPU overhead.
RMAN Active Duplicate functionality creates a clone or physical standby database over the network without the
use of backups. Data file copies are written directly to the destination database. In Oracle Database 12c, the
workload is moved to the destination server via auxiliary channels, relieving resource bottlenecks on the source
(usually, production) database server. New for Oracle Database 12c, Active Duplicate Cloning can use RMAN
compression and multi-section capabilities to further increase performance. Unused block compression happens
automatically. Administrators can, as before, also configure RMAN to apply binary compression, if network traffic
is a bottleneck.
Cross-platform Backup and Restore
New with Oracle Database 12c, RMAN Cross-platform functionality enables backup and restore across different
platforms, 5 for efficient tablespace and database migration. On the source platform, BACKUP creates backup
sets of user tablespaces, including Data Pump metadata dump file, in read-only mode. RESTORE on the
destination platform automatically performs data file endian conversion and plugs-in tablespaces. To minimize
read-only impact, we recommend taking incremental backups that are then converted and applied to restored
data files. Only the final incremental backup need be taken while tablespaces are in read-only mode.
RMAN support for Oracle Multitenant
RMAN also supports the multitenant architecture. The familiar BACKUP DATABASE / RESTORE DATABASE
command now backs up / restores the Multitenant Container Database (CDB), including all its Pluggable
Databases (PDBs). RMAN commands can also be applied to individual PDBs, including full backup and restore,
5 Cross-platform incremental backups are supported for Linux on earlier releases as described in MOS Note 1389592.1. Traditionally, moving a
database across platforms required either import/export or cross-platform transportable tablespaces procedures, seriously affecting application
using the keyword PLUGGABLE. For example, the following simple RMAN script can be run for Point-in-time
Recovery of a pluggable database:
RMAN also supports efficient cloning of the container database including all or some (user-specified) pluggable
Other RMAN Enhancements Available with Oracle Database 12c
RMAN can now recover individual database tables from backup, via a simple RECOVER TABLE command. This
recovers one or more tables (the most recent or an older version) from an RMAN backup. Tables can be
recovered in-place or to a different tablespace. Optionally, RMAN can create a Data Pump dump file of the
table(s). This functionality replaces an error-prone manual process and improves the Recovery Time Objective
(RTO). It extends the range of recovery where Flashback is not applicable, for example when a dropped table
has been purged out of the Recycle Bin, or when the desired point to recover is outside the window given by the
Other RMAN enhancements in Oracle Database 12c to provide increased performance and ease-of-use include:
» RMAN support for multi-section backup of image copies and incremental backups.
» Quick synchronization of a standby database with the primary database using simple RMAN command:
» Direct support for SQL statements by the RMAN command line (CLI) – no SQL keyword or quotes needed.
For more information see Oracle’s RMAN resources on OTN (
Fast Recovery Area
A key component of Oracle Database backup strategy is the Fast Recovery Area (FRA), a location on a
filesystem or ASM disk group for all recovery-related files and activities for an Oracle database. All the files
required to recover a database from media failure can reside in the FRA, including control files, archived logs,
data file copies, and RMAN backups. Oracle automatically manages space in the FRA. A single FRA may be
shared by one or more databases.
In addition to a location, the FRA is also assigned a quota. If multiple databases are sharing a single FRA, each
will have its own quota and the size of the FRA will be the sum of database quotas. When new backups are
created in the FRA and there is insufficient space (per the assigned quota) to hold them, backups and archived
logs that are not needed to satisfy the RMAN retention policy (or that have already been backed up to tape), are
deleted automatically to reclaim space. The FRA also notifies the administrator (via the alert log) when disk
space used is nearing its quota and no additional files can be deleted. The administrator can add more disk
space, back up files to tape to free up disk space for the FRA, or change the retention policy.
Data Recovery Advisor
Many data outages can be mitigated based on accurate analysis of errors and trace files that are present prior to
an outage. The Data Recovery Advisor (DRA) can proactively run database health checks that verify physical
integrity, identify possible precursors to a database outage, and alert the administrator. The administrator can get
recovery advice and perform preventive actions to fix the problem before it results in system downtime. When
critical business data are damaged, the DRA assists the database administrator to ensure a safe and fast
recovery under pressure, by quickly and thoroughly evaluating recovery and repair options. As it is tightly
integrated with other Oracle High Availability features such as Data Guard and RMAN, the DRA is able to identify
which recovery options are feasible given the specific conditions. These options are presented to the
administrator, ranked from least to most potential data loss. The DRA can also automatically implement the best
recovery option(s) or just serve as a guide for manual recovery by the administrator.
Backup to Tape – Oracle Secure Backup (OSB)
Oracle Secure Backup (OSB) is Oracle’s enterprise-grade tape backup management solution for both database
and file system data. Oracle Secure Backup delivers scalable, centralized tape backup management for
distributed, heterogeneous IT environments, by providing:
» Recovery Manager (RMAN) integration, supporting versions Oracle Database 10g to Oracle Database 12c,
that can increase backup performance by 25 – 40% over comparable products.
» File system data protection for UNIX, Windows, and Linux servers, as well as Network Attached Storage
(NAS) protection via the Network Data Management Protocol (NDMP).
» Policy-based fine-grained control, including backup encryption and key management, tape duplication, and
rotating tapes between different locations (vaulting).
» The Oracle Secure Backup environment may be managed using the command line, the OSB web tool or
Oracle Enterprise Manager.
The following enhancements in the latest release, OSB 10.4, are ideal for Exadata environments:
» Faster performance in NUMA (Non-Uniform Memory Access) environments. The Oracle database shadow
backup/restore process and OSB data service communicate via a shared memory area for data transfer
between the processes. On NUMA machines, OSB 10.4 ensures these processes run in the same NUMA
region(s) to deliver the fastest performance.
» Increased data transfer rates over InfiniBand (IB) by leveraging of RDS/RDMA (Reliable Datagram Socket
over Remote Direct Memory Access) instead of TCP / IP, which provides two key advantages. First, this can
reduce the number of media servers required to meet performance goals because more front-end throughput
allows using more tape drives per media server. 6 Second, media server(s) can use multiple IB ports versus
only one when using TCP/IP over InfiniBand as adapter bonding does not support TCP/IP over IB at this time
– only RDS / RDMA.
» Improved network utilization by load balancing network interfaces thereby increasing performance and
avoiding over / under use of any one interface. If a host contains more than one network interface of a
particular type, OSB 10.4 uses all the available interfaces of that type for the data connections between the
client host and the media server host. 7
6 For example, if throughput is 50% higher using RDS/RDMA over InfiniBand, this translates to 3GB/sec instead of 2GB/sec per media server with
one InfiniBand port.
7 OSB selects the type of network interface in this order: RDS/RDMA, InfiniBand, IPv6, IPv4.
Oracle Secure Backup Cloud Module
Cloud storage (such as Amazon’s S3) provides easy access to reliable offsite backups. With RMAN and the
Oracle Secure Backup Cloud module, you can send backups directly to Amazon S3, or back up locally and then
send a copy to the cloud. If the database is running on Amazon Web Services cloud servers, the OSB Cloud
module is an ideal data protection tool.
The OSB Cloud module can back up all supported versions of Oracle Database. 8 Administrators can continue to
use their existing backup tools – Enterprise Manager, RMAN scripts, etc. – to perform cloud backups. See OSB
resources on OTN for more information (
Real-Time Data Protection – Zero Data Loss Recovery Appliance
The Zero Data Loss Recovery Appliance is an innovative data protection solution that is completely integrated
with RMAN and the Oracle Database. 9 It eliminates data loss exposure and dramatically reduces data protection
overhead on production servers across the enterprise. The Recovery Appliance easily protects all databases in
the data center with a massively cloud-scale architecture, ensures end-to-end data validation, and fully
automates the management of the entire data protection lifecycle for all Oracle databases through the unified
Enterprise Manager Cloud Control interface.
The Recovery Appliance is an integrated hardware and software appliance that includes substantial technical
innovation that standardizes backup and recovery processes for Oracle databases across the entire data center.
The appliance offers the following unique advantages.
» It eliminates data loss by using proven Data Guard technology to transmit redo records, the fundamental unit
of transactional changes within a database. Protected databases transmit redo to the Recovery Appliance as
soon as it is generated, eliminating the requirement to take archived log backups at a production database.
The granularity and real-time nature of this unique level of protection allows databases to be protected up to
the last sub-second of data.
» Minimal impact backups – The Recovery Appliance’s Delta Push technology offloads backup operations from
production databases using a true incremental-forever backup strategy. Protected databases send RMAN
incremental backups to the Recovery Appliance after an initial full backup. RMAN block change tracking is
used to send deltas, resulting in effective source-side deduplication by only sending unique changes. Delta
Push eliminates recurring full backups and reduces bandwidth utilization. In addition, all overhead from RMAN
backup deletion / validation / maintenance operations and tape backups are offloaded to the Recovery
» Any point-in-time restore using Delta Store technology. The Recovery Appliance validates, compresses,
indexes and stores the incoming deltas. The deltas are the foundation of virtual full database backups, which
are essentially space-efficient pointer-based representations of physical full backups as of an incremental
backup point-in-time. When the time comes for a restore operation, Delta Store efficiently recreates a physical
full backup from appropriate incremental backup point. Archived log backups stored by the appliance are then
used to roll forward to the exact point in time desired. The Delta Store eliminates typical production server
overhead of traditional restore and apply of successive incremental backups. The performance of the restore
operation is further optimized by the scalability and performance of the underlying Exadata-based hardware
8 The OSB Cloud module uses the RMAN media management interface, which seamlessly integrates external backup libraries with RMAN for all
database backup and recovery operations.
» End-to-end data validation as deltas are received combined with on-disk background validation of existing
backups. Logical and physical validation using deep knowledge of Oracle block structure provides a level of
protection un-matched by other backup solutions.
» Secure replication of backups between Recovery Appliances. This protects against potential outages of a
Recovery Appliance and provides disaster protection against site outages. Deltas and redo can also be sent
directly from a protected database to a remote Recovery Appliance for disaster protection.
» Low cost, autonomous, 24x7 tape archival without impacting production database servers. The Recovery
Appliance comes pre-installed with Oracle Secure Backup (OSB) media management software. It supports a
16Gb Fibre Channel Adapter on each compute server within the appliance so that OSB can connect directly to
tape hardware without costly third party tape backup agents or specialized media servers.
» Cloud-Scale Data Protection. The Recovery Appliance introduces the concept of a protection policy, which
defines recovery window goals that are enforced on a per-database basis on the appliance and tape, if
present. Using protection policies, databases across the enterprise can be easily grouped by recovery service
» End-to-End visibility and management of the data protection life-cycle using Enterprise Manager Cloud
Control. Beginning from the time the backup is created by RMAN on the database, to the time it is stored on
disk, on tape, and/or replicated to another appliance in a remote data center. All backup locations are tracked
by the Recovery Appliance catalog. Any RMAN restore and recovery operation can retrieve the most
appropriate backups wherever they reside.
» Modern Cloud Scale Architecture. The Recovery Appliance is built on a massively scalable, highly redundant,
fault tolerant, storage architecture. As more and more databases within an enterprise are moved to the
recovery appliance, compute and storage servers are easily added to provide a simple, no-downtime, scaleout data protection cloud to support ongoing business growth. The base configuration consists of 2 compute
servers and 3 storage servers providing up to 37 TB of usable capacity for incoming backups. Storage servers
can be added to the rack to increase usable capacity to a maximum of 220TB as needs grow. When the first
rack is full, additional racks can then be connected via InfiniBand. Up to 18 fully configured racks can be
connected together providing up to 5.4 PB of usable capacity.
The Recovery Appliance is the ideal solution for enterprise backup and any-point in time recovery for Oracle
Databases. It is also the ideal disaster recovery solution for Oracle Databases that support applications that have
recovery time objectives that can be achieved by a restore from backup. Oracle Data Guard and Active Data
Guard, discussed in the following sections, are the solutions for applications with more aggressive recovery time
objectives that can only be achieved by fast failover to a running copy of the production database
Recovery from Logical Corruption: Oracle Flashback Technology
Human errors happen. Oracle Database Flashback Technologies are a unique and rich set of data recovery
solutions that enable reversing human errors by selectively and efficiently undoing the effects of a mistake.
Before Flashback, it might take minutes to damage a database but hours to recover it. With Flashback, the time
required to recover from an error is depends on the work done since the error was made. Recovery time does
not depend on the database size, a capability that becomes a necessity as database sizes continue to grow, and
that is unique to the Oracle Database. Flashback supports recovery at all levels including the row, transaction,
table, and the entire database.
Flashback is easy to use: the entire database can be recovered with a single short command, instead of
following a complex procedure. Flashback also provides fine-grained analysis and repair for localized damage,
e.g., when the wrong customer order is deleted. Flashback can also repair more widespread damage while still
avoiding long downtimes, e.g., all of yesterday’s customer orders have been deleted.
Flashback Query
Using Oracle Flashback Query, administrators are able to query any data at some point-in-time in the past. This
powerful feature can be used to view and logically reconstruct corrupted data that may have been deleted or
changed inadvertently. For example, a simple query such as:
displays rows from the emp table as of the specified time (a timestamp, obtained for example via a TO
TIMESTAMP conversion). Administrators can use Flashback Query to identify and resolve logical data
corruption. This functionality can also be built into an application to provide its users with a quick and easy
mechanism to undo erroneous changes to data without contacting their database administrator.
Flashback Versions Query
Flashback Versions Query enables administrators to retrieve different versions of a row across a specified time
interval instead of a single point-in-time. For instance, a query such as:
displays each version of the row between the specified timestamps, including the transactions that operated on
the row. The administrator can pinpoint when and how data has changed, providing great utility in both data
repair and application debugging.
Flashback Transaction Query
Logical corruption may also result when an erroneous transaction changes data in multiple rows or tables.
Flashback Transaction Query allows an administrator to see all the changes made by a specific transaction. For
instance, a query such as:
shows changes made by this transaction and it also produces the SQL statements necessary to undo (flashback)
the transaction (where transactionID may be obtained via a Flashback Versions Query). This precision tool
empowers the administrator to efficiently pinpoint and resolve logical corruptions in the database.
Flashback Transaction
Often, data failures take time to be identified, and additional ‘good’ transactions may have executed on data
logically corrupted by an earlier ‘bad’ transaction. In this situation, the administrator must analyze changes made
by the ‘bad’ transaction and by any other (dependent) transactions that subsequently modified the same data, to
ensure that undoing the ‘bad’ transaction preserves the original, correct state of the data. This analysis can be
laborious, especially for complex applications.
Flashback Transaction enables an administrator to flash back a single ‘bad’ transaction, and optionally, all of its
dependent transactions, with a single PL/SQL operation. Alternatively, an administrator can use an Enterprise
Manager wizard to identify and flash back the necessary transactions.
Flashback Database
To restore an entire database to a previous point-in-time, the traditional method is to restore the database from a
RMAN backup and recover to the point-in-time prior to the error. This takes time proportional to the (ever
growing) size of the database – hours or even days.
In contrast, Flashback Database, using Oracle-optimized flashback logs, can quickly restore an entire database
to a specific point-in-time. Flashback Database is fast because it restores changed blocks only. Flashback
Database can restore a whole database in minutes via a simple command like:
No complicated recovery procedures are required and there is no need to restore backups. Flashback Database
drastically reduces the downtime required for database point-in-time recovery. Also, Flashback Database
integrates with Data Guard to support Data Guard’s Snapshot Standby and the reinstatement of the previous
primary after a failover (see also the Data Guard section).
Flashback Table
When logical corruption is limited to one or a set of tables, Flashback Table allows the administrator to easily
recover the affected tables to a specific point-in-time. A query such as:
FLASHBACK TABLE orders, order_items TIMESTAMP time
will undo any updates to the orders and order_items tables made after the specified time.
Flashback Drop
Getting back an erroneously dropped table used to require restore, recovery, export/import, and re-creation of all
associated table attributes. With Flashback Drop, dropped tables can be easily recovered, via a FLASHBACK
TABLE <table> TO BEFORE DROP statement. This restores the dropped table and all of its indexes,
constraints, and triggers, from the Recycle Bin (logical container for dropped objects).
For more details, see Flashback resources OTN (
Real-time Data Protection and Availability – Oracle Data Guard
Enterprises need to protect their critical data and applications against events that can take an entire cluster or
data center offline. Human error, data corruptions or storage failures can make a cluster unavailable. Natural
disaster, power outages, and communications outages can affect the availability of an entire site. The Oracle
Database offers a variety of data protection solutions that can safeguard an enterprise from costly downtimes
due to cluster or site failures. Frequently updated and validated local and remote backups constitute the
foundation of an overall HA strategy. However, the complete restore of a multi-terabyte backup can take longer
than the enterprise can afford to wait and the backups may not contain the most up to date versions of data. For
these reasons enterprises often maintain one or more synchronized replicas of the production database in
separate data centers. Oracle provides several solutions that can be used for this purpose. Oracle Data Guard
and Active Data Guard are optimized to protect Oracle data providing both high availability and disaster recovery.
Data Guard is a comprehensive solution to eliminate single points of failure for mission critical Oracle Databases.
It prevents data loss and downtime simply and economically by maintaining a synchronized physical replica
(standby) of a production database (primary). Administrators can choose either manual or automatic failover to a
standby database if the primary database is unavailable. Client connections can quickly and automatically
failover to the standby and resume service.
Data Guard achieves the highest level of data protection through its deep Oracle Database integration , strong
fault isolation, and Oracle-aware data validation. System and software defects, data corruption, and administrator
errors that affect a primary database are not mirrored to the standby.
Data Guard provides a choice of either asynchronous (near zero data loss) or synchronous (zero data loss)
protection. Asynchronous configurations are simple to deploy, with no performance impact to the primary,
regardless of the distance that separates primary and standby databases. Synchronous transport, however, will
affect performance and thus imposes a practical limit to the distance between primary and standby database.
Performance is affected because the primary database does not proceed with the next transaction until the
standby acknowledges that changes for the current transaction are protected. The time spent waiting for
acknowledgement increases as the distance between primary and standby increases, directly affecting
application response time and throughput. Fast Sync and Active Data Guard Far Sync are two new capabilities
for Oracle Database 12c that address this limitation (see the Active Data Guard section for information on Far
Fast Sync
Fast Sync provides an easy way of improving performance in synchronous zero data loss configurations. Fast
Sync allows a standby to acknowledge the primary database as soon as it receives redo in memory, without
waiting for disk I/O to a standby redo log file. This reduces the impact of synchronous transport on primary
database performance by shortening the total round-trip time between primary and standby. Fast Sync is
included with Data Guard.
High Availability with Zero Data Loss across Any Distance: Active Data Guard
Active Data Guard is a superset of Data Guard functionality that includes a number of advanced capabilities for
data protection and high availability, as well as features that increase return on investment (ROI) in disaster
recovery systems. Several key capabilities are described below.
Increase ROI by Offloading Workloads to an Active Data Guard Standby
Active Data Guard enables the offloading of read-only reporting applications, ad-hoc queries, data extracts, and
so on, to an up-to-date physical standby database, while providing disaster protection. Active Data Guard relies
on a unique highly concurrent apply process for best performance, while also enforcing the same read
consistency model for read-only access at the standby as is enforced at the primary database. No other physical
or logical replication solution does this. This makes it attractive to offload read-only workloads to an active
standby, eliminating the cost of idle redundancy.
There are also many reporting applications that would be eligible to use a read-only database except for the
requirement that they write to global temporary tables and /or access unique sequences. Active Data Guard
includes new capabilities with Oracle Database 12c to allow writes to global temporary tables and access to
unique sequences at an active standby. This further expands the number of reporting applications that can be
offloaded from a primary database. No other physical or logical replication solution can provide all of these
capabilities: each alternative solution is deficient in one or more areas compared to Active Data Guard. Active
Data Guard is an option for Oracle Database Enterprise Edition.
Active Data Guard Far Sync: Zero Data Loss at any Distance
Active Data Guard Far Sync is a new capability for Oracle Database 12c that provides zero data loss protection
for a production database by maintaining a synchronized standby database located at any distance from the
primary location, without impacting database performance and with minimal cost or complexity. A far sync
instance (a new type of Data Guard destination) receives changes synchronously from a primary database and
forwards them asynchronously to a remote standby (see figure 2). Production can be quickly failed over,
manually or automatically, to the remote standby database with zero data loss.
Figure 2: Active Data Guard Far Sync – Zero Data Loss Protection at any Distance
A far sync instance is a light-weight entity that manages a control file and log files. It requires a fraction of the
CPU, memory, and I/O resources of a standby database. It does not keep user data files, nor does it run
recovery. Its only purpose is to transparently relieve a primary database from serving remote destinations. A far
sync instance can save network bandwidth by performing transport compression using the Oracle Advanced
Compression option.
Consider an asynchronous Data Guard configuration with a primary in New York, and a standby in London.
Upgrade to zero data loss simply by using Active Data Guard to deploy a far sync instance within synchronous
replication distance of New York (less than 150 miles). There is no disruption to the existing environment nor is
there any requirement for proprietary storage, specialized networking, more database licenses, or complex
See also Data Guard and Active Data Guard resources on OTN (
Active Data Guard Automatic Block Repair
Block-level data loss usually results from intermittent I/O errors, as well as memory corruptions that get written to
disk. When Oracle Database reads a block and detects corruption it marks the block as corrupt and reports the
error to the application. No subsequent read of the block will be successful until the block is recovered manually,
unless you are using Active Data Guard. With Active Data Guard, block media recovery happens automatically
and transparently. Active Data Guard repairs physical corruption on a primary database using a good version of
the block retrieved from the standby. Conversely, corrupt blocks detected on the standby database are
automatically repaired using the good version from the primary database.
Active-Active HA: GoldenGate
Data Guard physical replication is optimized for a specific purpose – simple, transparent, one-way physical
replication for optimal data protection and availability. Oracle GoldenGate, in contrast, is a feature-rich logical
replication product with advanced features that support multi-master replication, hub and spoke deployment,
subset replication and data transformation, providing customers flexible options to fully address their replication
requirements. GoldenGate also supports replication between a broad range of heterogeneous hardware
platforms and database management systems beyond Oracle.
Figure 3: Oracle GoldenGate – Active-Active Bi-Directional Replication
Applications can use GoldenGate with minimal modification or special handling. GoldenGate can be configured,
for example, to capture changes for an entire database, or a set of schemas, or individual tables. Databases
using Oracle GoldenGate technology can be heterogeneous – e.g. a mix of Oracle, DB2, SQL Server, etc. These
databases may be hosted in different platforms – e.g. Linux, Solaris, Windows, etc. Participating databases can
also maintain different data structures using GoldenGate to transform the data into the appropriate format. All
these capabilities enable large enterprises to simplify their IT environment by making GoldenGate a single
standard for replication technology.
Active – Active HA
In a GoldenGate active-active configuration, both the source and destination databases are available for reading
and writing, yielding a distributed configuration where any workload can be balanced across any participating
database. This provides high availability and data protection should an individual site fail. It also provides an
excellent way to perform zero downtime maintenance – by implementing changes in one replica, synchronizing it
with a source database operating at the prior version, and then gradually transitioning users with zero downtime
to the replica operating at the new version.
Because users in a GoldenGate active-active configuration can update different copies of the same table
anywhere, update conflicts may result from changes made to the same data element in different databases at the
same time. Oracle GoldenGate provides a variety of options for avoiding, detecting, and resolving conflicts.
These options can be implemented globally, on an object-by-object basis, based on data values and filters, or
through event-driven criteria, including database error messages. For more information, see GoldenGate
resources on OTN (
Complete Site Failover: Oracle Site Guard
Oracle Site Guard is part of Oracle Enterprise Manager Cloud Control 12c, and extends automation of disaster
recovery to the rest of the Oracle stack. Oracle Site Guard enables administrators to automate complete site
failover. Site Guard eliminates the need for specialized skill sets by relieving IT staff of the burden of manually
executing complex failover operations, thus reducing the likelihood of human error that can lead to extended
downtime and data loss. Site Guard orchestrates the coordinated failover of Oracle Fusion Middleware, Oracle
Databases, and is extensible to include other data center components. Site Guard integrates with underlying
replication mechanisms that synchronize primary and standby environments and protect mission critical data;
Oracle Data Guard for Oracle data, and storage replication for file system data external to the Database.
Addressing Planned Downtime
Planned downtime is typically scheduled to provide administrators with a window to perform system and/or
application maintenance. During these maintenance windows, administrators take backups, repair or add
hardware components, upgrade or patch software packages, and modify application components including data,
code, and database structures. Oracle has recognized the need to minimize or eliminate planned downtime while
performing these system and maintenance activities. Oracle Database 12c enables planned maintenance to be
performed online to the production version of the database, or in rolling fashion using a synchronized copy of the
production database, or using bi-directional replication between two copies of the production database to migrate
from one version to the next with zero downtime. The following sections address these capabilities.
Online System Reconfiguration
Oracle supports dynamic online system reconfiguration for all components of your Oracle hardware stack.
Oracle’s Automatic Storage Management (ASM) has built-in capabilities that allow the online addition or removal
of ASM disks. When disks are added or removed from an ASM Diskgroup – Oracle automatically rebalances the
data across the new storage configuration while storage, database, and application remain online. Real
Application Clusters (RAC) provides powerful online reconfiguration capabilities. Administrators can dynamically
add and remove clustered nodes without any disruption to the database or the application. Oracle also supports
the dynamic addition or removal of CPUs on SMP servers that have this online capability. Finally, Oracle’s
dynamic shared memory tuning capabilities allow administrators to grow and shrink the shared memory and
database cache online. With automatic memory tuning capabilities, administrators can let Oracle automate the
sizing and distribution of shared memory according to Oracle’s analysis of memory usage characteristics.
Oracle’s extensive online reconfiguration capabilities support administrators’ ability to not only minimize system
downtime due to maintenance activities – but to also enable enterprises to scale capacity on demand.
Online Data and Application Change
Online data and schema reorganization improves overall database availability and reduces planned downtime by
allowing users full access to the database throughout the reorganization process. For example, adding columns
with a default value has no effect on database availability or performance. Many data definition language (DDL)
maintenance operations allow administrators to specify timeouts on lock waits, to maintain a highly available
environment while performing maintenance operations and schema upgrades. Also, indexes can be created with
the INVISIBLE attribute so the Cost-Based Optimizer (CBO) ignores them although they are still maintained by
DML operations. Once an index is ready for production, a simple ALTER INDEX statement will make it visible to
the CBO.
Online Data File Move and Online Partition Move
Oracle Database 12c has the ability to move a data file while users are accessing its data, via command ALTER
DATABASE MOVE DATAFILE. This capability maintains data availability during maintenance operations. This
capability is useful to move infrequently accessed datafiles to lower-cost storage. Another example of use is to
move a database from non-ASM to ASM storage.
Online Partition Move, a new capability for Oracle Database 12c, makes it easier to compress online. It supports
online, multi-partition redefinition in a single session.
Online Table Redefinition
As business requirements evolve, so too do the applications and databases supporting the business. Through
the strategic use of the DBMS_REDEFINITION package (also available in Enterprise Manager) – administrators
can reduce downtime in database maintenance by allowing changes to a table structure while continuing to
support an online production system. Administrators using this API enable end users to access the original table,
including insert/update/delete operations, while the maintenance process modifies an interim copy of the table.
The interim table is routinely synchronized with the original table and once the maintenance procedures are
complete, the administrator performs the final synchronization and activates the newly structured table.
Enhancements to Online Table redefinition in Oracle Database 12c include:
» Online redefinition of tables with VPD policies with new parameter copy_vpd_opt in start_redef_table.
» Single command redefinition with new REDEF_TABLE procedure.
» Improved sync_interim_table performance, improved resilience of finish_redef_table with better lock
management, and better availability for partition redefinition with only partition-level locks, and improved
performance by logging changes for only the specified partitions.
Online Application Upgrades: Edition-Based Redefinition
Oracle Database’s Edition-Based Redefinition feature allows the online upgrade of an application with
uninterrupted availability of the application. When the installation of the upgrade is complete, the pre-upgrade
application and the post-upgrade application can be used at the same time. This means that an existing session
can continue to use the pre-upgrade application until its user ends it, while all new sessions use the post-upgrade
application. Once all sessions that use the pre-upgrade application end, the old edition can be retired. Thus the
application as a whole enjoys hot rollover from the pre-upgrade version to the post-upgrade version. Editionbased Redefinition introduces a scope -- an edition:
» Code changes are installed in the privacy of a new edition.
» Data changes are made safely, by writing only to new columns or new tables not seen by the old edition. An
editioning view exposes a different projection of a table into each edition so each sees just its own columns.
» A crossedition trigger propagates data changes made by the old edition into the new edition’s columns, or (in
hot-rollover) vice-versa.
Hot Patching
Online patching, which is integrated with OPatch, provides the ability to patch the processes in an Oracle
instance without bringing the instance down. Each process associated with the instance checks for patched code
at a safe execution point, and then copies the code into its process space.
Rolling Patch Upgrades using Oracle RAC
Oracle supports the application of patches to the nodes of a Real Application Cluster (RAC) system in a rolling
fashion, maintaining the database available throughout the patching process. To perform the rolling upgrade, one
of the instances is quiesced and patched while the other instance(s) in the server pool continue in service. This
process repeats until all instances are patched. The rolling upgrade method can be used for Patch Set Updates
(PSUs), Critical Patch Updates (CPUs), one-off database and diagnostic patches using OPATCH, operating
system upgrades, and hardware upgrades.
Data Guard Standby-First Patch Assurance
Data Guard Standby-First Patch Assurance (Oracle Database onward) enables physical standby to
support different software patch levels between a primary and standby database for the purpose of applying and
validating Oracle patches in rolling fashion. 10 Eligible patches include:
» Patch Set Update, Critical Patch Update, Patch Set Exception, and Oracle Database bundled patch, and full
release upgrades.
» Oracle Exadata Database Machine bundled patch, Exadata Storage Server Software patch.
Database Rolling Upgrades using Data Guard
The transient logical database rolling upgrade process uses a Data Guard physical standby database to install a
complete Oracle Database patch set (Oracle to, or major release (Oracle 11.2 to 12.1), or
perform other types of maintenance that change the logical structure of a database. The process begins with a
primary and physical standby database. The standby is upgraded first as usual, except in this case Data Guard
logical replication (SQL Apply) is used on a temporary basis to synchronize across old and new versions. Unlike
Redo Apply, logical replication uses SQL to replicate across versions and thus is unaffected by differences in
physical redo structure that may exist between different Oracle releases.
A switchover moves production to the new version on the standby database after the upgrade and
resynchronization with the original primary is complete. The original primary is then flashed back to the point
where the upgrade process began and converted to a physical standby of the new primary. The physical standby
is mounted in a new Oracle home, upgraded and resynchronized using redo generated by the new primary (a
second catalog upgrade is not required).
Database Rolling Upgrades using Active Data Guard
Although the database rolling upgrade process described above is very effective at reducing planned downtime,
it is a manual procedure with many steps and thus error-prone. This creates reluctance to use the rolling upgrade
process that results in users accepting longer downtimes associated with traditional upgrade methods.
Traditional upgrade methods also increase risk because maintenance is performed on the production database
BEFORE it is possible to be certain of the outcome.
Database Rolling Upgrades using Active Data Guard, a new capability for Oracle Database 12c, solves this
problem by replacing forty-plus manual steps required to perform a rolling database upgrade with three PL/SQL
packages that automate much of the process. This automation helps minimize planned downtime and reduce risk
by implementing and thoroughly validating all changes on a complete replica of production before moving users
to the new version.
You can use this capability for database version upgrades starting from the first patchset of Oracle Database
12c. 11 You can use it for other database maintenance tasks with Oracle Database 12c. 12
10 See MOS Note 1265700.1 for more information on Standby-First Patch Apply eligible patches.
11 You must still the Transient Logical Standby upgrade when upgrading from Oracle Database 11g to Oracle Database12c, or from Oracle
Database 12.1 to the first patchset of Oracle Database 12.1.
12 Maintenance tasks include: partitioning non-partitioned tables, changing BasicFiles LOBs to SecureFiles LOBs, moving CLOB-stored XMLType
to binary XML-stored, altering tables to be OLTP-compressed.
Platform Migration, Systems Maintenance, Data Center Moves
Data Guard also offers some flexibility for primary and standby databases to run on systems having different
operating system or hardware architectures, providing a very simple method for platform migration with minimal
downtime. 13 Data Guard can also be used to easily migrate to ASM and/or to move from single instance Oracle
Databases to Oracle RAC, as well as for data center moves, with minimal downtime and risk. Oracle GoldenGate
offers the most flexibility for platform migration between heterogeneous platforms with minimal or zero downtime.
Zero Downtime Maintenance using Oracle GoldenGate
Oracle GoldenGate is the most flexible method for reducing or eliminating planned downtime. Its heterogeneous
replication can support virtually any platform migration, technology refresh, database upgrade, and many
application upgrades that change back-end database objects, with minimal or zero downtime. GoldenGate logical
replication is able to keep databases on different platforms or versions synchronized. This enables changes to be
implemented on a copy of production, then synchronized with the old version. Once validated, users are switched
to the copy running at the new version or on the new platform. GoldenGate one-way replication does require
some downtime while all users are disconnected from the old version and reconnect to the new. GoldenGate
bidirectional replication using conflict resolution enables gradual migration of users from the old version for zero
Managing Oracle Database High Availability Solutions
Oracle Enterprise Manager Cloud Control 12c is the management interface for an Oracle environment. Cloud
Control delivers centralized management functionality for the complete Oracle IT infrastructure, including
systems running Oracle and non-Oracle technologies. With a broad set of administration, configuration
management, provisioning, end-to-end monitoring, and security capabilities, Oracle Cloud Control reduces the
cost and complexity of managing complex environments, while helping customers maintain their required IT
infrastructure service levels.
Oracle Enterprise Manager Cloud Control 12c includes key HA capabilities, as follows:
» It offers a High Availability Console that integrates monitoring of various HA areas (e.g. clustering, backup &
recovery, replication, disaster recovery), provides overall HA configuration status and initiates appropriate
» The Maximum Availability Architecture Configuration Advisor page allows you to evaluate the configuration
and identify solutions for protection from server, site, storage, human and data corruption failures, enabling
workflows to implement Oracle recommended solutions.
» It enables further MAA automation by enabling migration of databases to ASM and conversion of single
instance databases to Oracle RAC with minimum downtime.
» It supports management of the Oracle Secure Backup administrative server and Oracle Secure Backup File
System backup/restore and reporting.
Global Data Services
Many customers have offloaded read-only and read-mostly workloads to their Active Data Guard Standby
replicas. Oracle GoldenGate replication also enables distributing workloads over multiple databases, both within
13 See MOS Note 413484.1 for details on platform combinations supported in a Data Guard configuration.
and across datacenters. In replicated multi-data center architectures, dynamic, transparent, and automated load
balancing and high availability are difficult to implement and operate.
Global Data Services (GDS), a new capability for Oracle Database 12c, addresses those challenges, by
extending the familiar notion of Database Services to span multiple database instances in near and far locations.
GDS extends RAC-like failover, service management, and service load balancing to replicated database
configurations (see Figure 4). GDS provides inter- and intra-region load balancing across replicated databases.
For example, it can distribute load across a reader farm composed of standby instances, and even direct read
traffic to the primary if conditions warrant it.GDS is intended for applications that are replication-aware.
Global Data Services (GDS) benefits include:
» Higher Availability by supporting service failover across local and global databases.
» Better Scalability by providing load balancing across multiple databases.
» Better Manageability via centralized administration of global resources.
In addition to your existing Oracle Databases, GDS requires one or more Global Services Manager (GSMs), and
a GDS Catalog Database. Each region has its own GSM (plus replicas for HA), which is a server with specialized
software that monitors database load and availability and directs workload appropriately. To the application layer
(the clients using the database services), the GSM looks like a listener. The GDS Catalog is a database (one for
the whole GDS framework, but replicated for HA) that hosts the metadata required for GDS to operate, in a
manner similar to the RMAN Catalog’s hosting of backup metadata. The GSMs and the GDS Catalog act in
concert with new GDS functionality in Oracle Database 12c.
Figure 4: Global Data Services for Failover and Load Balancing Across Datacenters
In the GDS example in figure 4, Data Guard role transitions (switchover/failover) are performed as ususal, but in
this case GDS is aware that the role transition has occurred and directs connections (read-write or read-only) as
appropriate. With Active Data Guard, GDS supports:
» Service failover and load balancing across replicated databases in local and remote data centers.
» Automatic role-based services upon Data Guard role transitions.
» Load balancing for reader farms.
With GoldenGate, GDS supports failover and load balancing for local and remote data centers. When Active
Data Guard and Oracle GoldenGate allow offloading production workloads to the replication assets, GDS
enables better replica utilization, yielding better performance, scalability and availability.
Successful enterprises deploy and operate highly available technology infrastructures to protect critical data and
information systems. At the core of many mission critical information systems is the Oracle database, responsible
for the availability, security, and reliability of the information technology infrastructure. Building on decades of
innovation, Oracle Database 12c continues to improve its world-class availability and data protection solutions to
maximize data and application availability, in the event of both planned maintenance activities and of unexpected
Oracle’s MAA best practices empower customers to achieve their high availability goals by deploying resources
and technology commensurate to their requirements and constraints. These best practices enable customers to
attain HA on a range of platforms and deployments. MAA applies to database deployments on low-cost
commodity servers, where availability and performance are enhanced by horizontal scalability. MAA also applies
to high-end, storage and general purpose servers. Last, but not least, Oracle’s engineered systems are built from
the ground up following MAA. Customers seeking extreme performance with maximum availability deploy Oracle
Exadata Database Machines as the core of their database-centric IT infrastructure. The same deep
understanding of IT infrastructure and database technology that underlies Oracle’s MAA best practices, with
proven success in thousands of global, mission critical deployments, also underlies Oracle Exadata Database
Oracle’s HA solutions have widespread customer adoption and continue to be a critical differentiator when
choosing a database technology to support the 24x7 uptime requirements of today’s businesses. Review Oracle
HA customer success stories across various industry verticals worldwide at
Appendix: New High Availability Features in Oracle Database 12c
Protects applications from database session failures due to instance, server, storage, network or any
other related component. Application Continuity re-plays affected “in-flight” requests so that the failure of
a RAC node appears to the application as a slightly delayed execution.
Flex ASM
Increases database (instance) availability, facilitation cluster-based database consolidation, by enabling
inter-node storage failover and reducing ASM-related resource consumption by up to 60%.
ASM Disk
Checks for logical corruptions and repairs them automatically, in both normal and high-redundancy disk
groups. This complements the health checks that RMAN performs during backup and recovery.
Data Guard
Allows a standby to acknowledge the primary database as soon as it receives redo in memory, without
Fast Sync
waiting for disk I/O to a standby redo log file.
Data Guard
Provides zero data loss protection for a production database by maintaining a synchronized standby
Far Sync
database located at any distance from the primary location with minimal cost or complexity.
Global Data
Extends Database Services to span multiple database instances in near and far locations. GDS extends
Services (GDS)
RAC-like failover, service management, and service load balancing to a set of replicated databases.
Oracle Secure
Faster performance in NUMA (Non-Uniform Memory Access) environments. Increased data transfer
Backup (OSB)
rates over InfiniBand (IB) by leveraging of RDS/RDMA instead of TCP / IP. Improved network utilization
by load balancing network interfaces.
RMAN and the
The BACKUP DATABASE / RESTORE DATABASE command now backs up / restores the Multitenant
Container Database (CDB), including all its Pluggable Databases (PDBs). RMAN commands can also
be applied to individual PDBs, including full backup and restore, using the keyword PLUGGABLE.
RMAN backup and restore across different platforms for efficient tablespace and database migration.
Other Recovery
Can recover the most recent or an older version of an individual database table from a backup; tables
can be recovered in-place or to a different tablespace. Multi-section backup of image copies and
incremental backups. Quick synchronization of a standby database with the primary database using a
command. Direct support for SQL statements by the RMAN command line – no SQL keyword needed.
Online Move
Online Data Move enables moving a data file while users are accessing its data,
Online Partition Move supports online, multi-partition redefinition in a single session.
Online Table
Single command redefinition. Improved sync_interim_table performance, improved resilience of
finish_redef_table with better lock management, better availability for partition redefinition with only
partition-level locks, and improved performance by logging changes for only the specified partitions
Upgrades with
Replaces dozens of steps required to perform a rolling database upgrade with 3 PL/SQL packages that
Active Data
automate much of the process. Minimizes planned downtime and risk by implementing and thoroughly
validating all changes on a complete replica of production before moving users to the new version.
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Redwood Shores, CA 94065, USA
Fax: +1.650.506.7200
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