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Modes of Usage and Optimizing Performance 105
Modes of Usage and
Optimizing Performance
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
www.hp.com/support
.
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 LVD-compliant. 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.
System Performance
Drives can write data at 30 MB/s (native) or 60 MB/s (2:1 compression).
However, to get this performance it is essential that your whole system can
deliver this performance.
Typical areas where bottlenecks can occur are:
3
Disk system (a single hard disk drive will not be able to deliver 60 MB/s
transfer rates).
3
Some file systems are able to transfer data faster than others.
3
The type of data being backed up can affect backup performance (for
example, file sizes and compressibility).
3
Some backup software performs better than others.
To improve performance you may like to consider a RAIDed disk solution with
a large number of physical hard disks.
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.
Data Transfer Rate
Adaptive Tape Speed (ATS) enables the drive to “stream” data at variable
tape speed, which means that it maintains a continuous data flow to tape
even when the transfer speed varies. This is automatically managed by the