On Thu, 21 Oct 1999, 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:
How are you decicing that it is only 12GB? If you are looking at the
details of the specific tape and it shows 12GB used and 0GB free then
things are working right. That window shows the data that arkeia has put
on the tape. Remember that the data is already compressed. So you are
seeing the physical amount of data that the drive wrote to the tape, but
when you look at the fact that the data stream that got written was
already compressed you see that the logical amount written is more. If
you look at the log output from the backup you will see the compression
ratio that it achieved and do the math.
> - What are the right dip switch settings of the DAT24?
I've found that hardware and software compression equals bloated results.
The software compression by arkeia wins over the hardware compression for
our DLT library and our HP library, which is the same one you have.
> - 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
>
