Adaptec | 39160 - SCSI Card Storage Controller U160 160 MBps | Troubleshooting Tape Drive Hardware

Troubleshooting Tape Drive Hardware
STORAGE
Applying a Modular, Layered Approach to
Troubleshooting Tape Drive Hardware
In storage environments, tape drives and libraries can be cost-effective backup and
restore devices, but they may incur support costs for troubleshooting and maintenance.
This article introduces a modular, layered approach that can ease system administration of tape devices by methodically troubleshooting problems to determine root
causes and resolve issues.
BY GAJANAN MUDALIAR
Related Categories:
Dell PowerVault storage
I
n the typical enterprise data center, tape drives, tape
Troubleshooting at the hardware layer
libraries, and other tape automation devices can be
The scope of the hardware layer extends from the tape
cost-effective workhorses for offline data storage. How-
drive to the SCSI cable connectivity of a SCSI controller.
ever, the total cost of ownership for the many tape devices
Loose cable connections can cause problems at this layer.
Microsoft Windows
attached to a data center’s servers can escalate when
Administrators can perform the following troubleshoot-
Novell NetWare
support and service costs are factored into the equation.
ing procedures to diagnose tape device problems at the
Given these considerations, administrators must take a
hardware layer:
Linux
Storage
Tape library
proactive approach to troubleshooting, determining root
causes, and correcting problems.
Troubleshooting
A basic system for troubleshooting tape drive devices
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can be categorized in a four-layer stack, similar to a TCP/IP
for the complete category index to
stack. As shown in Figure 1, the predominant layers include
all articles published in this issue.
the hardware layer, the BIOS layer, the OS layer, and the
•
Check for improper SCSI termination, which can
lead to SCSI errors during backups or to the tape
Application layer
OS layer
application layer.
Although the hardware layer and the BIOS layer can
BIOS layer
be combined into a single layer, various troubleshooting
techniques can be carried out independently on each of
Hardware layer
these layers. This article provides details and troubleshooting techniques for the four layers.
42
DELL POWER SOLUTIONS
Figure 1. Layered model for modular approach to troubleshooting
Reprinted from Dell Power Solutions, May 2005. Copyright © 2005 Dell Inc. All rights reserved.
May 2005
STORAGE
device not being detected on the BIOS level.
•
•
Check that the SCSI installation is properly configured—
that the SCSI Disconnection and Parity settings are enabled.
terminators must exist at both ends of the bus. Most host
Synchronous Negotiation should be disabled. The SCSI trans-
bus adapters (HBAs) are terminated by default, so be sure
fer rate should be set to 5 Mbps.2 If hard drives are being
that the last device in the chain is also terminated.1
•
Check the configuration of the SCSI host adapter and ensure
Determine how the SCSI device is terminated. Some SCSI
duplexed, both SCSI cards should be configured identically.
•
Make sure that the SCSI card is set to use Edge Triggering
devices are internally terminated, which can be disabled
and not Level Triggering. Level Triggering involves the use of
through a jumper or a dual in-line package (DIP) switch,
shared interrupts, which can cause problems in some systems.
while others use an external terminator plug.
Troubleshooting at the OS layer
Tape drives and libraries usually perform a power-on self-test
If the tape drive is detected on the BIOS level, it should also be
(POST) operation, in which the system initializes itself and initi-
detected on the OS level. To facilitate device detection, adminis-
ates an internal self-test to check for hardware issues. Some tape
trators should proactively check
drives and tape libraries have a display panel, which provides a hex
with hardware vendors for
code that corresponds to the hardware error that occurred within
updated device drivers.
A basic system for
troubleshooting tape drive
the system. The hex code may indicate a self-diagnostic mode or a
particular display of blinking or colored lights. Consult the device
Microsoft Windows OS
documentation for more information.
The Microsoft ® Management
devices can be categorized
Console (MMC) provides a
Troubleshooting at the BIOS layer
user interface through which
If a tape drive is not detected on the BIOS level of a controller, the
administrators can coordi-
problem usually resides in the controller or the tape drive. Admin-
nate systems management
istrators can perform the following troubleshooting procedures to
for Microsoft Windows® envi-
determine why a tape drive is not being detected:
ronments. In the Computer
in a four-layer stack. The
predominant layers include
the hardware layer, the
Management>Device Manager
•
•
BIOS layer, the OS layer, and
Change the SCSI ID of the tape drive or library to deter-
menu, administrators can
mine whether the SCSI ID is causing the problem. For
view all hardware compo-
example, the tape drive’s SCSI ID could conflict with a
nents within the Windows-
device on the same SCSI bus, which usually occurs when
based environment. From this
the SCSI ID of the tape drive is 7—the default SCSI ID of
menu, they can check whether a tape device is listed. The “?”
the HBA (SCSI controller). When attaching a tape drive
icon beside a tape device indicates that the device driver is not
with a SCSI ID above 7 on a narrow SCSI channel, change
loaded for that particular device. Device drivers usually can be
the SCSI ID to a value below 7.
downloaded from the vendor’s Web site or from the CD provided
Check all the other devices in the SCSI chain. If one of the
by the vendor.
the application layer.
devices on the same SCSI bus is not responding, it should be
•
separated from the SCSI bus.
Novell NetWare OS
Check the compatibility matrix of the tape drive to determine
System administrators managing systems within Novell® NetWare®
whether the controller is supported. Commonly used HBAs in
environments can troubleshoot tape hardware from the command-
Dell™ servers include the Adaptec SCSI Card 39160 and SCSI
line interface. To check whether a tape drive is listed in NetWare,
Card 29160 and the LSI Logic LSI53C1030 embedded SCSI
administrators should issue the following command:
controller.
•
Check for incompatibility between standards. For example, if
list storage adapters
a tape drive is connected to a narrow SCSI channel controller,
the narrow SCSI channel can support only seven SCSI IDs.
1 If
Sample output of the preceding command is shown in Figure 2.
both internal and external devices are attached to one host adapter, it may be necessary to disable the termination on the adapter card if it is physically located in the middle of the bus.
2 Different
host adapters will set these parameters in different ways. Some utilize jumpers or DIP switches, while others use a software-based configuration utility. Not all host adapters will be capable of adjusting all of
these parameters.
www.dell.com/powersolutions
Reprinted from Dell Power Solutions, May 2005. Copyright © 2005 Dell Inc. All rights reserved.
DELL POWER SOLUTIONS
43
STORAGE
The following command will list only the devices
NW2600:list devices
attached to the system:
0x0007: [V025-A0-D0:0] SAMSUNG CD-ROM SN-124 N104 [CD]
0x0008: [V024-A5-D1:0] Legacy Floppy [FLOPPY]
list devices
0x0009: [V321-A4-D1:0] IBM
ULTRIUM-TD2
37RH [TAPE]
0x000B: [V358-A1-D0:0] FUJITSU MAP3367NC rev:5608 [HDD]
Sample output of the preceding command is shown
0x000C: [V358-A1-D1:0] FUJITSU MAP3367NC rev:5608 [HDD]
in Figure 3.
0x000D: [V358-A1-D2:0] FUJITSU MAP3367NC rev:5608 [HDD]
If the device cannot be viewed on the OS level,
0x000E: [V358-A1-D6:0] Unbound Device Object
administrators should issue the following command to
scan all the SCSI buses:
Figure 3. Sample output for Novell NetWare command to list devices attached to the system
scan for new devices
Linux OS
In the device list output, the NetWare OS may not list the
In Linux, /proc/scsi/scsi is the file that shows the inquiry string
tape drive with its actual name or it may list the tape drive as
for the tape drive. The /var/log/dmesg file will have an entry for
an “unbound device object.” In such cases, a proper compatible
the tape drive after the kudzu utility is executed and the device
driver should be loaded so that the output will reflect the inquiry
driver of the controller is loaded. If a tape library has a changer
name of the tape drive. The common device driver for all tape
module and the tape drive and changer have the same SCSI ID but
devices is nwtape.cdm. For Digital Linear Tape (DLT) tape devices,
reside in different LUNs—which can occur on Dell PowerVault™
the common driver is dlttape.cdm.
122T autoloaders with DLT VS 80 technology—the Linux kernel
If the SCSI card is enabled for logical storage units (LUNs),
will not update the /proc/scsi/scsi file with the inquiry string. In
the changer and tape drive may be using the same SCSI ID but
this case, system administrators should update the file with the
different LUNs. If so, administrators must enable LUN support. For
following command:
example, if using an Adaptec SCSI card, the administrator would
add LUN_ENABLE=FF to the line that is loading the driver for this
card in startup.ncf:
echo “scsi add-single-device 2 0 0 13” >
/proc/scsi/scsi
In the preceding command, the four numbers refer to the
LOAD AHA2940.HAM SLOT=HBA slot number
r LUN_ENABLE=FF
HBA ID (2), the SCSI bus (0), the SCSI ID (0), and the LUN (13).
LOAD SYM8XXNW.HAM SLOT=HBA slot number
r /LUN
Devices in Linux are referenced by a
device file. A device file can be a raw
NW2600:list storage adapters
device file or a logical device file.
0x00 [V100-A100] USB UHCI Controller [slot 0]
0x01 [V025-A0] Novell ATA/IDE Host Adapter Module [slot 10008]
0x07 [V025-A0-D0:0] SAMSUNG CD-ROM SN-124 N104
0x02 [V358-A1] LSI_53C1030:10023 [slot 10023]
Because a tape drive is a sequential
device, it can be referenced using a
raw device path.
The Dell support Web site
0x0E [V358-A1-D6:0] Unbound Device Object
0x0B [V358-A1-D0:0] FUJITSU MAP3367NC rev:5608
(support.dell.com) provides numer-
0x0C [V358-A1-D1:0] FUJITSU MAP3367NC rev:5608
ous tools to help troubleshoot
0x0D [V358-A1-D2:0] FUJITSU MAP3367NC rev:5608
hardware-related tape device issues.
0x03 [V358-A2] LSI_53C1030:10024 [slot 10024]
Administrators also can initiate a self-
0x04 [V321-A3] Adaptec SCSI Card 39160/3960D - Ultra160 SCSI [slot 201]
diagnostic test to obtain an error code
0x05 [V321-A4] Adaptec SCSI Card 39160/3960D - Ultra160 SCSI [slot 202]
and messages on the front panel of
0x0A [V321-A4-D4:0] DELL
PV-132T
227D
the tape device. The user guide of the
0x09 [V321-A4-D1:0] IBM
ULTRIUM-TD2
37RH
tape device can then provide addi-
0x06 [V024-A5] Legacy FLOPPY Controller [slot 0]
0x08 [V024-A5-D1:0] Legacy Floppy
tional information about the error
code and troubleshooting steps to
help resolve the issue.
Figure 2. Sample output for Novell NetWare command to list storage devices
44
DELL POWER SOLUTIONS
Reprinted from Dell Power Solutions, May 2005. Copyright © 2005 Dell Inc. All rights reserved.
May 2005
STORAGE
Troubleshooting at the application layer
System administrators
From the application layer, it is often difficult to drill down to the
root cause of problems because most applications do not interact
commands so that they can
managing systems within
with the hardware directly. Application software generally communicates with the device drivers through the OS kernel, and
can troubleshoot tape
•
target—the device that
receives service requests
command-line interface.
•
or hardware errors occur
in the backup device, the
hardware from the
problems at the application layer:
•
the SCSI bus.
Whenever SCSI errors
to communicate with storage units. Administrators can perform
the following troubleshooting procedures to diagnose tape device
check the conditions and the
trace communications over
Novell NetWare environments
the device drivers communicate with the firmware of the storage
unit. Some applications may have native device drivers loaded
with all the respective SCSI
Check for wear and tear of the Linear Tape-Open (LTO) tape
for processing—sets a unit
attention (UA) flag, which
drive, which can prevent tape media from being populated to
eventually follows a SCSI reset condition. Administrators can deter-
maximum capacity.
mine the cause of a SCSI bus reset by taking a SCSI trace of the
Clean the tape head using a cleaning cartridge if a significant
communication path between the target and the initiator—a SCSI
amount of debris has accumulated on the head. Media debris
device containing application clients and SCSI ports that originate
can prevent data from being written to a tape cartridge.
device service and task management requests to be processed by a
Check whether the device is supported by the applica-
SCSI target device. Obtaining the sense data information from the
tion and whether the appropriate device drivers have been
SCSI trace session can show which flags have been set and help
installed if the tape hardware is not detected on the applica-
administrators identify a clear path to problem resolution.
tion level but is detected on the OS level.
•
Check the vendor’s Web site to determine whether an
Efficiently resolving tape hardware problems
updated version of the tape device firmware is available if
Administrators can enhance the process of troubleshooting tape
SCSI errors occur while backing up large amounts of data.3
devices by following the modular, layered approach described in
this article. To determine root causes rapidly, administrators should
Software vendors typically provide diagnostic utilities to aid in
first categorize the condition as a hardware issue or a software
hardware troubleshooting. For example, VERITAS NetBackup soft-
issue, then determine the layer at which to begin troubleshoot-
ware includes a utility through which administrators can initiate a
ing. This method can help administrators find an efficient path
self-diagnostic confidence test on the tape device.
to problem resolution.
Troubleshooting other general operational issues
Gajanan Mudaliar is an engineering analyst on the tape storage engineering team in the Dell Product Group. His primary area of expertise is
testing and troubleshooting tape hardware and automation devices. Prior
to joining Dell, Gajanan had seven years of IT experience in technical support and system administration for enterprise storage installations. He
has a B.E. in Electronics and Telecommunication from the University of
Kolhapur in India.
Tape drives can break down during a backup or restore procedure.
In Windows, administrators would detect this error in a system
event log; in Linux and
The Microsoft Management
NetWare, the error would
appear on the system con-
Console provides a user
sole or logger screen.
In some cases, to deter-
interface through which
mine the root cause of a failure, administrators must take
administrators can coordinate
a SCSI trace and then analyze
F OR M ORE INF ORM ATION
it on a SCSI analyzer. SCSI
systems management
analyzers show time diagrams, command listings,
for Microsoft Windows
and state listings. When
using SCSI analyzers, admin-
environments.
Dell support:
support.dell.com
VERITAS support:
support.veritas.com
istrators should be familiar
3 As a general safety rule, do not disconnect or power down the tape device during the firmware upgrade.
46
DELL POWER SOLUTIONS
Reprinted from Dell Power Solutions, May 2005. Copyright © 2005 Dell Inc. All rights reserved.
May 2005
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