Exploit Storage Resources for SAP on IBM i

Exploit Storage Resources for
SAP on IBM i
A summary of options to boost performance and reduce the storage
footprint of SAP systems running on IBM i
Ron Schmerbauch
IBM Systems and Technology Group ISV Enablement
May 2016
© Copyright IBM Corporation, 2016
Table of Contents
Document Change History....................................................................................................... 1
Abstract..................................................................................................................................... 2
About the Authors .................................................................................................................... 2
Prerequisites............................................................................................................................. 2
Introduction .............................................................................................................................. 3
Recommendations ................................................................................................................... 5
Software Options ...................................................................................................................... 6
SAP housekeeping to remove unnecessary data .................................................................................... 6
SAP Basis Tables Clean-Up ............................................................................................. 6
Deleting Client Copies ....................................................................................................... 6
Batch Input Processing Clean-Up ..................................................................................... 6
Change and Transport System Clean-Up ......................................................................... 7
SAP Data Management Guidelines and Archiving .................................................................................. 7
Other options to clean up SAP data ........................................................................................................ 7
IBM i: Journal settings to reduce journal receiver sizes .......................................................................... 8
DB2 for IBM i: Automatic reuse of deleted rows ...................................................................................... 8
DB2 for IBM i: Automatic index balancing ............................................................................................... 8
Hardware Options..................................................................................................................... 9
Hardware Tape Compression .................................................................................................................. 9
Parallel Tapes .......................................................................................................................................... 9
IBM System Storage Copy Services ........................................................................................................ 9
Mirroring ............................................................................................................................ 9
FlashCopy ....................................................................................................................... 10
Real Time Disk Compression ................................................................................................................ 10
Summary ................................................................................................................................. 11
Resources ............................................................................................................................... 11
Trademarks and special notices ........................................................................................... 12
Exploit Storage Resources for SAP on IBM i
Document Change History
Version
October 2012
May 2014
June 2016
Changes
Initial version
Correct transaction name to SM36.
Adjust authors list, note SVC compression support allows
for more HW options beyond V7000
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Abstract
This paper provides a summary of the various options that are available to reduce the size of an SAP
system running on the IBM i operating system and DB2 database. Performance of SAP applications
and system maintenance tasks will improve due to the reduced data volume. Also described are
hardware based solutions to improve the performance of such tasks.
About the Authors
Ron Schmerbauch is the technical leader of the SAP on IBM i team, part of IBM i Development in
Rochester. He has many years of experience with SAP on IBM i, beginning with the original porting effort
of SAP R/3 to OS/400® in 1994. Before joining the SAP team, Ron worked in Database development. He
holds a degree in Computer Science from the University of Southern California. He can be reached at
rschmerb@us.ibm.com.
Prerequisites
You are running SAP systems on the IBM i operating system and DB2 for i database platform.
You are looking for ways to reduce the storage footprint of your SAP systems.
You want to backup and restore your systems faster and use fewer tapes.
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Introduction
Over time, SAP applications store ever larger amounts of data in file and database systems and can
eventually present challenges to any server platform. For example, the database size can have an impact
to the overall system performance each day. Specific operations such as building indexes over large
tables can take more time when more data is present. Not only the performance of maintenance tasks like
backup and restore is affected by the file system and database size, also SAP release upgrades and
enhancement package installations will run faster with less data in the system.
With SAP NetWeaver 7.5, certain files may grow in size as a result of manual “declustering” processes,
raising the priority of efficient handling of large tables. More information about this may be found in SAP
Note 1892354.
There are several opportunities available to address these types of challenges. In general, one can either
reduce the amount of data that is handled or one can more efficiently handle the data. The following
sections of the document summarize those options. They are grouped by software and hardware provided
options. If you are looking for a solution to a specific problem, the following table quickly guides you to the
appropriate sections.
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Ways to… reduce disk
speed up
requirements application
performance
in general
Page
speed up
save
operations
speed up
restore
operations
Section
reduce
number of
tapes
required for
backups
speed up avoid database
system
reorganizations
copy/clone
6
SAP Basis Tables
Clean-Up
x
x
x
x
x
x
x
6
Deleting Client
Copies
x
x
x
x
x
x
x
6
Batch Input
Processing CleanUp
x
x
x
x
x
x
x
7
Change and
Transport System
Clean-Up
x
x
x
x
7
SAP Data
Management
Guidelines and
Archiving
x
x
x
x
x
x
x
8
IBM i: Journal
settings to reduce
journal receiver
sizes
x
x
x
x
x
8
DB2 for IBM i:
Automatic index
balancing
x
x
x
x
x
x
x
x
x
x
x
x
x
x
8
DB2 for IBM i:
Automatic reuse of
deleted rows
9
Mirroring
x
9
Hardware Tape
Compression
9
Parallel Tapes
10
Real Time Disk
Compression
x
10
FlashCopy
x
x
x
x
x
x
x
x
Exploit Storage Resources for SAP on IBM i
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x
Recommendations
The options available and summarized in this paper differ in the amount of storage saved, effort required
and performance gained. Some options may not apply to your SAP system. If you don’t want to do
everything listed in this paper, we recommend that you perform the options in this order:
1.
2. DB2 for IBM i: Automatic reuse of deleted rows and DB2 for IBM i: Automatic index balancing are
taken care of by the DB2 for i database.. You still want to read the sections to know what it is
about.
3. Check your IBM i: Journal settings to reduce journal receiver sizes.
4. Do SAP Basis Tables Clean-Up and Change and Transport System Clean-Up. If you do batch
inputs to your SAP systems, also do Batch Input Processing Clean-Up.
5. Consider Deleting Client Copies, if you have any unused clients.
6. Not enough? Follow the instructions for SAP Data Management Guidelines and Archiving. This will
probably generate the most in storage savings and a noticeable performance boost.
7. If you are still looking for fewer tapes and/or faster backup times, consider the hardware provided
Hardware Tape Compression, Parallel Tapes, Mirroring and FlashCopy.
8. Consider Real Time Disk Compression for minimizing the amount of disk storage required for the
remaining data.
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Software Options
This section summarizes SAP, IBM i operating system and DB2 for i database provided options to reduce
the volume of data that is being used by the SAP systems.
SAP housekeeping to remove unnecessary data
There are a number of background jobs pre-defined in an SAP system that will do the basic housekeeping
in your SAP system. These jobs need to be scheduled to prevent certain files and database tables from
growing unnecessarily. Starting with SAP release R/3 4.6C, the standard jobs can be scheduled by calling
transaction SM36 and clicking on the ‘Standard Jobs’ button. Then click on ‘Default Scheduling’ to
schedule all standard clean-up jobs. SAP note 16083 - Standard jobs, reorganization jobs contains more
details about the standard jobs. Also for SAP releases prior to R/3 4.6C this note contains instructions how
to schedule the standard jobs manually. Check note 1411877 - New standard jobs to verify that you’ve
scheduled all necessary jobs.
Besides the standard jobs, there are more areas in an SAP system that need clean-up from time to time.
Those areas are listed in the following sections.
SAP Basis Tables Clean-Up
SAP systems are using a number of database tables to store administrative data. Those called basis
tables may grow in size over time and affect system performance. There are more than 50 different
categories of basis tables like application log tables, IDoc and RFC related tables. Each table category
has its own clean-up method, ranging from simple deletion of data to specific archiving procedures.
SAP note 706478 - Preventing Basis tables from increasing considerably contains the full list of basis
table categories and the according clean-up methods. Most of the clean-up methods are described in
their own SAP note which is listed in note 706478.
Deleting Client Copies
Client copies occupy space in the database. If there are client copies that are not needed, consider
deleting those to save space. Existing clients in your system are listed in transaction SCC4. Clients
can be deleted with transaction SCC5. SAP note 70643 - CC-TOPIC: Client Deletion (SCC5)
describes known issues when deleting a client copy.
Batch Input Processing Clean-Up
Batch input processing can be used to import data from non-SAP systems into SAP. When this is
done periodically, the according log files and administrative table entries can occupy a large amount of
disk space.
Batch input log files can be cleaned-up by running report RSBDC_REORG, which is a newer version
of report RSBDCREO. The report has an input screen that lets you choose batch sessions by name
and time window to reorganize batch input files. SAP note 147354 - Batch input: Reorg. and delete
sessions and logs describes how the report works. SAP note 18307 - Batch input logs and
reorganization describes more technical details of the batch input log reorganization report
RSBDCREO.
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The APQD table is used to store batch input session information. This table can grow significantly over
time if you have many incomplete batch input sessions or sessions marked as “keep”. SAP note
36781 - Table APQD is very large describes preventive measures how to keep table APQD small and
actions how to reduce its size when the table is large already.
Change and Transport System Clean-Up
The change and transport system which is used to distribute changes between various SAP systems
is using files in the file system and database tables to store administrative data and the transport
requests itself. Without regular clean-up, the transport file system directories and database tables can
become very large.
When you import many transport requests individually instead of using the mass transport feature,
those individual transports request remain on the import queue as already imported. The import queue
grows in size over time, and among other effects displaying the queue takes longer. SAP note 565574
- Deleting imported entries from TMS import queue explains how to remove entries from the import
queue that are already imported.
Transport data in the file system that is no longer needed, like log files and old transport requests, can
be deleted by calling the TP program with the ‘clearold’ option. SAP note 41732 - Deletion of data in
transport directory contains detailed information about the procedure.
SAP Data Management Guidelines and Archiving
SAP systems often contain many more years of history than are required to satisfy the current needs of
the business. The SAP Data Management Guidelines document provides comprehensive information
about how to handle application data growth. It describes archiving strategies for the most common SAP
Business Suite applications ERP and CRM and database tables that are common to all SAP NetWeaver
based applications. The document can be downloaded from the Information Lifecycle Management section
of the SAP Service Marketplace (service.sap.com/ilm) under the Data Archiving topic.
A special topic is reducing the data volume of profit center accounting. The following SAP notes cover size
reduction options for profit center accounting:

203545 - Archiv. profit center: Analysis of table GLPCA

178919 - Table GLPCA: How to reduce the data volume?

91615 - Archiving/profit center: new archiving programs
Other options to clean up SAP data
The following SAP notes contain information about further clean-up options:

1401395 - Report to clean up residual data in user tables

16513 - File system is full - what do I do?
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IBM i: Journal settings to reduce journal receiver sizes
Database journals are used to keep track of changes to database table entries. The journal entries are
stored in journal receiver objects. Although the journal receiver objects are usually saved and then deleted
from the system periodically, they still may occupy larger storage space between the save and delete
points. The journal settings RCVSIZOPT and MINENTDTA influence the size of the journal receiver
objects. To minimize the journal receiver sizes in one easy step that never needs to be repeated, use the
IBM i CHGJRN command to set RCVSIZOPT(*MINFIXLEN) and MINENTDTA(*FILE). For further
information about the journal settings see SAP note 1449715 - IBM i: Current recommendations for journal
configuration.
DB2 for IBM i: Automatic reuse of deleted rows
When deleting records from a database table, the free space will be reused by the DB2 for i database
automatically, unless the “Reuse deleted records (REUSEDLT)” option is set to *NO for that table. The
default setting for all SAP tables is *YES for REUSEDLT. Therefore no reorganization of database tables
is necessary during normal system operation.
If you have deleted many rows from the database, for example during archiving or client deletion, you may
want to immediately regain the free storage space. Then you can use the Reorganize Physical File
Member (RGZPFM) command. SAP note 84081- iSeries: Reorganization of database tables (RGZPFM)
contains important information about how to use the RGZPFM command in an SAP environment.
DB2 for IBM i: Automatic index balancing
As data in a database is changed and deleted, the associated indexes are updated to reflect the data
changes. Depending on the order that data is added and changed, the underlying data structure (typically
based on a binary tree) can become unbalanced. On other systems, an administrator would manually rebalance the underlying data structure by reorganizing the system.
Although there is no action necessary to enable it, you should be aware that on the IBM i platform, the
database engine is continually monitoring the underlying index structure and rebalancing the index
structure internally when necessary. This allows your applications to continue running without having to
take the system down for index reorganization.
Automatic rebalancing also makes sure that each index is no larger than necessary.
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Hardware Options
This section summarizes options that are provided by hardware solutions to address the challenges posed
by SAP systems with large data volumes.
Hardware Tape Compression
If reducing the number of tapes that must be managed or used for each save operation is desired,
hardware tape compression can be an answer.
Many tape devices support data compression, which increases the apparent capacity of your media by
encoding the data to use less space. The data is compressed and decompressed by the hardware each
time it is read or written on your tape device and is not apparent to applications.
Depending on the device, compression ratios are often in the 2:1 or 3:1 range. Therefore it can be
possible to reduce the number of required tapes by half or more by taking advantage of devices featuring
hardware tape compression.
Parallel Tapes
If reducing the time it takes to perform a save or restore operation is desired, one option is to use more
than one tape device in parallel. It is possible to use the tape compression techniques described in the
previous section together with parallel tape strategies.
One way this can be done is manually by using multiple save or restore operations, each operating on
specific objects concurrently.
IBM i Backup, Recovery and Media Services (BRMS) may be used to control automated methods of
saving and restoring multiple objects. Two strategies exist, parallel-parallel or parallel-serial. Parallelparallel will split individual objects across tapes, while parallel-serial is keeping objects intact on a tape, but
saving multiple objects in parallel.
All three methods are described at: www.ibm.com/developerworks/mydeveloperworks/wikis/home/wiki/IBM
Backup, Recovery and Media Services (BRMS) for i/page/IBM i parallel save and restore?lang=en
IBM System Storage Copy Services
IBM System Storage copy services may be used to address more than one aspect of large SAP data
volumes.
Mirroring
Mirroring can be used to create and maintain an exact duplicate of a set of disk volumes, even for
large data sets. Once a copy is created, it can be taken offline so that operations one might want to
perform on it that can take a significant amount of time such as a save operation can be performed
without impacting the performance on the original copy. Mirroring is provided by many IBM System
Storage solutions. Refer to www.ibm.com/systems/storage for most current information.
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FlashCopy
FlashCopy can be used to quickly create an exact duplicate of a set of disk volumes, even for large
data sets. When creating a copy of an existing system, a flash copy will be much faster than
performing a save then a restore operation. FlashCopy functionality for IBM i is provided by IBM
System Storage solutions Storwize V7000, SAN Volume Controller, XIV and DS8000. Further storage
systems may support FlashCopy in the future. Refer to www.ibm.com/systems/storage for most
current support information.
Real Time Disk Compression
If you are interested in reducing the amount of disk capacity required by SAP components on an IBM i
LPAR, you might consider compressing the disk volumes associated with that LPAR. Real time disk
compression reduces the amount of required disk space without significant impact to the I/O response
time for most workloads. Compressing an entire LPAR is easy to do and, best of all, requires no ongoing
administration effort.
Some database platforms offer file based compression. This requires choosing which files in the database
to compress, followed by an ongoing monitoring effort to make sure the efficiencies are not lost over time.
Administrators on other platforms must also manage the frequency of table and tablespace
reorganizations, which generally require downtime.
The disk compression rate for a typical SAP ERP system is between 50 and 70 percent. It should be noted
that compressed disk volumes remain compressed when flash copied. However, when data is delivered to
the server for processing it is decompressed. In this case hardware tape compression could be used to
recompress the data as it is saved.
The real time disk compression feature is currently available for IBM Storwize Family members, most
prominently V7000, and storage devices behind an SAN Volume Controller(SVC). The IBM Redpiece
“Real-time Compression in SAN Volume Controller and Storwize V7000”, available at
www.redbooks.ibm.com/redbooks.nsf/RedpieceAbstracts/redp4859.html?Open, contains more detailed
information about how to use the compression feature.
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Summary
On any platform, SAP solutions can eventually result in very large databases and/or file systems.
The IBM i platform automatically works to minimize the amount of data capacity necessary, most notably
with automated index balancing and the reuse of deleted records.
SAP administrators have opportunities from within the SAP application to reduce the size of the database
and file system by either archiving or deleting data that is no longer necessary to have in the active
system. They can also easily minimize the size required by the IBM i journal receivers with little effort by
running a IBM i command.
Hardware options such as disk compression, tape compression and parallel tape drives can also be
employed to handle large data volumes as efficiently as possible. FlashCopy and Mirroring technologies
provide options for working with snapshots of large datasets in an offline manner.
Resources
These websites provide useful references to supplement the information contained in this paper:

The SAP developer community network (SAP SCN) offers a SAP on IBM i space with discussion
forum, blog articles and other featured content for SAP on IBM i: scn.sap.com/community/ibm-i

The IBM information page for SAP on IBM i contains latest news and links to the current info
APAR for SAP on IBM i: www.ibm.com/developerworks/ibmi/sap

An IBM Redbook providing a technical deep dive into all aspects of a SAP on IBM i installation is
available from the IBM Redbooks website at www.redbooks.ibm.com/abstracts/sg247166.html
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Trademarks and special notices
© Copyright IBM Corporation 2012. All rights Reserved.
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Exploit Storage Resources for SAP on IBM i
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presented here to communicate IBM's current investment and development activities as a good faith effort
to help with our customers' future planning.
Performance is based on measurements and projections using standard IBM benchmarks in a controlled
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