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Performance Bottleneck Identification
In many cases, backup and restore performance using the VLS is limited by external factors. For
example, performance is affected by the speed at which data can be transferred to and from the
source disk system (the system being backed up), or by the performance of the Ethernet or Fibre
Channel SAN link from the source to the VLS. To locate bottlenecks in the system, HP provides
some performance tools which are part of the Library and Tape Tools package available at
www.hp.com/support/tapetools.
The HP Library and Tape Tools:
Dev Perf – This provides a simple test which will write data directly from system memory to a
cartridge in a library on the VLS. If this tool is run on a server being used as the backup media
server, it can provide the maximum data throughput rate for a single backup or restore process.
This isolates any backup application or source disk system from the environment and helps
identify whether the bottleneck is the VLS or the data transport link (Ethernet or Fibre Channel
SAN) to the VLS. This test should report 100- 1 50 MB on a VLS. Before starting the test, HP
recommends creating a new virtual library to avoid overwriting any data on the current
libraries. Use the frontpanel function on the Library and Tape Tools to manually "move"
a cartridge into the tape drive.
Sys Perf – This tool provides two tests which are conducted on the source disk system to perform
backup and restore performance tests. These tests either read (for backup) or write (for restore)
from and to the system disks to calculate how fast data can be transferred from disk and
therefore whether this is a bottleneck. These tests should be run on the media server which
backs up to the VLS. In order to test how fast any client servers can transfer data, the same
performance tests can be used by mounting a directory from any of the client servers to the
media server then running the test from the media server against these mounted directories;
this will show how quickly data can be transferred from the client server disk right through to
the media server.
Backup SAN Design Guidelines
The design of your SAN environment will affect the performance, efficiency, and reliability of your
backup and recovery scheme. Good SAN design is conducive to good VLS performance. Inefficient
SAN design can degrade the performance and efficiency of all members of the SAN.
General SAN Design Considerations
See the reference materials at
SAN design and configuration
Synchronizing equipment and firmware (heterogeneous SAN support)
Working across operating systems (SAN in heterogeneous environments)
SAN Zoning
Due to complexities in multi-hosting tape devices on SANs, it helps to make use of zoning tools to
help keep the backup/restore environment simple and less susceptible to the effects of changing
or problematic SANs. Zoning provides a way for servers, disk arrays, and tape controllers to only
see what hosts and targets they need to see and use. See the Enterprise Backup Solutions Design
Guide available at
The benefits of zoning include:
The potential to greatly reduce target and LUN shifting.
Limiting unnecessary discoveries on the FC interfaces.
Reducing stress on backup devices by polling agents.
www.hp.com/go/ebs
http://www.hp.com/go/ebs
for information about:
for details.
Performance Bottleneck Identification
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