HP StoreEver Ultrium Tape Drives - Manual (Page 60)

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 1840 tape drive can write uncompressed data at up to 120 MB/s (432 GB/hour)
• The Ultrium 960 tape drive can write uncompressed data at up to 80 MB/s (288 GB/hour)
• The Ultrium 460 tape drive can write uncompressed data at up to 30 MB/s (108 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 1840 or
960 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 460 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 1840 or 960 tape drive
because the Ethernet infrastructure connecting such systems may limit performance.
For Ultrium 460 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.
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).
Use Ultrium 1.6 TB or Ultrium WORM 1.6 TB cartridges with Ultrium 1840 tape drives, Ultrium 800
GB or Ultrium WORM 800 GB cartridges with Ultrium 960 tape drives, and Ultrium 400 GB or
Ultrium WORM 400 GB cartridges with Ultrium 460 tape drives.
• Data and file types
The type of data being backed up or restored can affect performance. Typically, small files incur
greater overhead in processing and access than large files. Equally, data that is not compressible
60 Diagnostic Tools and Performance