Re: [Dump-users] performance difference??

[Marc T. <ma...@dr...>]

On Tue, 20 Sep 2005, Ken Godee wrote:

> So I guess this is not a dump issue, dump appears to be doing its
> job. I'll look towards drivers/tape drive (firmware?) etc.
>
> Next I'll just swap tape drives and see if transfer rates change any.

Investigate the mt / mt-st commands to check what density you're writing 
to tape at, and whether tape drive compression is enabled or not.
# mt -f /dev/nst0 status

On some systems stinit(8) configures tapes at boot. Compare the 
/etc/stinit.def (if it exists) on both systems.

You may find one system is writing fixed size tape blocks, and the other 
at a variable block size. Try forcing the CentOS machine to a variable 
block size as with some drives this really helps streaming throughput:
# mt -f /dev/nst0 setblk 0

Experiment with the various parameters and see what works best for you.

Regards,
Marc