HP StoreEver Ultrium Tape Drives - Manual (Page 58)

Performance Assessment Tools
NOTE:
We strongly recommend that you check the information on our web site at http://www.hp.com/support/
pat . This contains detailed support information that will enable you to identify bottlenecks and take full
advantage of the performance capabilities of the Ultrium family of tape drives.
You can use our free, standalone performance assessment tools to check tape performance and test
whether your disk subsystem can supply data at the maximum transfer rate.
The tools are located online at
http://www.hp.com/support/pat . They are also integrated into HP
Library & Tape Tools, which is available both online ( http://www.hp.com/support/tapetools ) and
on the CD-ROM supplied with your tape drive.
Optimizing performance
Various factors can affect tape drive performance, particularly in a network environment. In nearly all
cases when performance is not as expected, it is the data rates of the disk subsystem that cause the
bottleneck.
If your tape drive is not performing as well as expected—for example, if backup windows are longer
than expected—please try the tools and consider the following points before contacting HP Support at
http://www.hp.com/support .
Can your system deliver the required performance?
• The Ultrium 1760 tape drive can write uncompressed data at up to 80 MB/s (288 GB/hour).
• The Ultrium 920 tape drive can write uncompressed data at up to 60 MB/s (216 GB/hour).
• The Ultrium 448 tape drive can write uncompressed data at up to 24 MB/s (86 GB/hour).
• The Ultrium 232 tape drive can write uncompressed data at up to 16 MB/s (59.6 GB/hour).
To obtain this performance it is essential that your whole system can deliver this performance. In most
cases, the backup application will provide details of the average time taken at the end of the backup.
Typical areas where bottlenecks can occur are:
• Disk subsystem
A single spindle disk will not be able to deliver good data throughput for an Ultrium 1760 or
Ultrium 920 tape drive at any compression ratio. To maximize the capability of these tape drives,
utilize aggregated disk sources (RAID) with multiple disk spindles.
A single spindle disk may be sufficient for an Ultrium 448 or 232 tape drive, depending on
your data’s compressibility. Best practice to ensure good throughput is to utilize multiple disk
spindles or data sources.
• System architecture
Be aware of the architecture of your data protection environment; multiple clients backed up over
a network may mean you are unable to take advantage of the Ultrium 1760 or Ultrium 920 tape
drive because the Ethernet infrastructure connecting such systems may limit performance.
For Ultrium 448 and 232 tape drives, the aggregation of multiple client sources over a network
provides a good way of delivering good performance, but anything less than Gigabit Ethernet
may limit performance for Ultrium 448 tape drives.
Some enterprise class backup applications can be made to interleave data from multiple sources,
such as clients or disks, to keep the tape drive working at optimum performance.
• Tape media type
The data cartridge should match the specification of the tape drive. A lower specification will
have a lower transfer speed (see “ Data cartridges ” on page 47). Use:
• Ultrium 1.6 TB R/W or Ultrium 1.6 TB WORM cartridges with Ultrium 1760 tape drives
• Ultrium 800 GB R/W or Ultrium 800 GB WORM cartridges with Ultrium 920 tape drives
58 Diagnostic Tools and Performance