Device properties - Block & Buffer settings

[Rob_Raymond]

I am running V10.0 Veritas Backup Exec and the backup works fine most of the time but every now and then (can be once a week or sometimes more often) the backup over runs and takes much longer than normal.

I found what was causing this, the block size and buffer size seem to reset back to the veritas default settings i.e. 1k & 32k.

If I set the block size to 64k and the buffer size 512k the backup runs as expected, within reasonable time etc.

What I would like to know is, is there a way of setting the default settings in veritas to be 64k & 512k? or are these settings (i.e 1k & 32k) picked up from the tape drive itself?

The server hasn't been rebooted or the veritas services dont restart so i'm not sure why these settings change every now and then?

Any help would be much appreciated.

[Shilpa_pawar_2]

Hi,

Changing Preferred Configuration settings is generally not recommended and may have a negative effect on your backup and system performance.

In case you still wish to change these settings please contact your hardware vendor. Following is the relevant information:
Block size: Some devices (for example, DLT drives) provide better performance when larger block sizes are used. Backup Exec does not ensure that the requested block size is in fact supported by that drive. You
should check the drive specifications to make sure that the block size is supported. If the drive does not support a block size, it will default to
its standard block size.
Buffer size: Depending on the amount of memory in your system, increasing this value may improve drive performance. The buffer size must be an even multiple of the block size. Each type of drive requires a different buffer size to achieve maximum throughput.
Buffer count: Depending on the amount of memory in your system, increasing this value may improve drive performance. If you change the buffer count,you may need to adjust the high water count accordingly.

Also refer: http://support.veritas.com/docs/259030

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