HP StorageWorks Ultrium Full-Height SCSI Tape Drives User Guide (EH853-90905, August 2007)

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.
Thetoolsarelocatedonlineath
ttp://www.hp.com/support/pat. They are also integrated into HP
Library & Tape Tools, which is available both online (h
ttp://www.hp.com/support/tapetoo ls)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 per
formance 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
h
ttp://www.hp.com/support.
Can your system deliver the required performance?
• The U ltrium 1840 tape drive can write uncompressed data at up to 120 M B/s (432 GB/hour)
• The Ultrium 960 tape drive can write uncompressed data at up to 80 MB/s (288 G B/hour)
• TheUltrium460tapedrivecanwriteuncompresseddataatupto30MB/s(108GB/hour)
To o b tain 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 o ccur are:
• Disk subsystem
AsinglespindlediskwillnotbeabletodelivergooddatathroughputforanUltrium1840or
960 tape drive at any compression ratio. To maximize the capability of these tape drives, utilize
aggregated disk sources (RAID) with multiple disk spindles.
Asinglespindlediskmaybesufficient for an Ultrium 460 tape drive, depending on your d ata’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
anetworkmaymeanyouareunabletotakeadvantageoftheUltrium1840or960tapedrive
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 per formance, 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 per formance.
• Tape media t ype
The d ata cartridge should m atch the specification of the tape drive. A lower specification will have a
lowertransferspeed(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 car tridges 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
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Diagnostic Tools and Per formance