On Sun, Mar 01, 2009 at 08:42:19PM +1100, Glen Vassileff wrote:
> We've been struggling to tune up remote NDMP backups to windows media 
> server with LTO-4 and disk storage units attached across 1Gb network.
> So far we've been getting around 25-30MB/s (40 at the very best with 2 
> streams to 2 tape drives) with 16 buffers x 64k each (or 63k each).
> 
>    * I wonder if anyone has experienced better performance and what
>      parameters have been used.

Haven't been able to use remote in the past.  I'll be trying to spin
some up in the next few months.  But mine will be all Linux.

>    * What can we expect if we are to connect LTO-4 fibre drives
>      directly to NetApp? Is it worth the effort in terms of significant
>      performance improvement?

Depends on the filer, the loading on the filer (overworked filers tend
to sacrifice NDMP performance for user operations), filesystem layout
(small files kill, direct or remote)...  That said, I can push my fast
filers to 80MB/s on LTO3.  I think I'm max on many of them due to
uncompressible data.  I've tried LTO4, but didn't get a huge speed
boost.  Probably maxing something out.  But I did average 100MB/s plus
on a couple of tests.

That's all single-stream performance (easiest thing to look at in NBU).
Two streams doesn't seem to slow stuff down for me significantly.  User
ops kills me more than a second stream tends to.

-- 
Darren
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