Optimizing Performance - HP StorageWorks DAT 40m Getting Started Manual

Optimizing performance

Various factors can affect tape drive performance, particularly in a network environment or if
the drive is not on a dedicated SCSI bus.
If your tape drive is not performing as well as expected, consider the following points before
contacting HP Support at
• Is the tape drive connected to a suitably-rated built-in SCSI bus or HBA, see "Why is the
SCSI bus type important?" on page 4. Suitably-rated means an Ultra Wide or higher SCSI
specification.
• Is the tape drive on a dedicated SCSI bus? For optimum performance, we recommend that
the tape drive is the only device on the SCSI bus. If it is not, ensure other devices are the
same SCSI specification as your tape drive model. If they are single-ended, the bus will
switch to single-ended mode with a lower transfer speed. There will also be restrictions on
cable length. Do not put tape drives and hard disks on the same SCSI bus.
• Is the SCSI bus terminated correctly. The last device on the SCSI bus must be terminated. Use
a multimode terminator.
• Is the cabling correct? Use properly-rated cables and adhere to maximum cabling length.
See the SCSI topic in the online User's Guide on the HP StorageWorks Tape CD-ROM for
more information about cable length.
• Have you installed the correct device drivers for your operating system and backup
application? See "Backup software and drivers" on page 5.
• Are you backing up across a network? The network load may be affecting the speed of
transfer or your backup application may only be appropriate for a single-server
environment.
• Is the backup application writing buffers at the correct speed? You may need to tune the
transfer, buffer and block size settings to optimize the speed that the application writes data
to the tape drive. HP StorageWorks DAT tape drives have an internal buffer of 8 MB.
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