i've found that software compression (with our cheesy seagate backup
exec s/w anyway..) compresses better than hardware because it is able to
reorganize the data in a more compressible manner rather than the drive
just compressing whatever hits the buffer.
we average just under 18GB per tape w/ full compression, although i have
seen instances where it would hit 20GB. it's extremely data dependant i
would expect.
then again, i could just be talking out of my ass again... :)
-s
Thomas Seidel wrote:
>
> I'm sorry this is a bit off-topic, but large raid sets need big backups ;-)
> My HP SureStore DAT24 stops after writing 12 GB of data to a DDS-3 tape. I
> suspect there must be something wrong with the compression. To verify this I
> need some additional information:
>
> - What are the right dip switch settings of the DAT24?
> - Did 'mt datcomression 2' really switch the compression on??
> - What is the best block size for the dump command???
> - Any other topics I have to look for????
>
> Oh, the box: kernel 2.2.9 & Adaptec AHA-2940 at 10 MB/s narrow sync, Dual
> Processor Board with two PII/400
>
> Thanx
> Thomas
