On 19/04/12 17:10, John Drescher wrote:

> Bacula defaults to fixed blocks of ~ 64K. This will work with all LTO
> drives but can be suboptimal in performance. You can change the block
> settings in bacula-sd.conf however I believe that will make all tapes
> that were written with the 64K blocks unusable without you manually
> erasing the tape. I am stuck on 64K blocks for my LTO2 drive for that
> very reason.

as far as I've been able to tell from tests, you can't mix block sizes
on one tape, however small block sizes continue to be readable for
restores after changover and they will be written with large block sizes
after being relabelled

IE: The only requirement is to close off all open volumes before
changing block size.

"Can be suboptimal" is an understatement - especially on LTO4-5.

LTO has supported 16Mb blocks since LTO2 but bacula only writes up to
2Mb - even that gives a big speed boost over 64k - which is ok for DATs
but nothing faster than that.

> 
> John
> 
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