On Thu, 2009-04-09 at 07:45 -0500, Les Mikesell wrote:
> Thomas Karcher wrote:
> > Hi Ski,
> > 
> >>> Performance is of course not really great but surprisingly good. I
> >>> evaluated (very shortly) against mounting via NFS, and NFS just sucks
> >>> with backuppc.
> >> I think it depends on the NFS server you are using.  I have over 1500
> >> clients backing up via 7 backuppc servers attached via nfs to a high
> >> performance Exastore NAS device.  Works great.
> > 
> > Ah, yes, that's possible, I have a much "cheaper" environment - and also
> > a setup smaller by magnitudes. I had the impression that many very small
> > disk accesses (as backuppc does when checking for newer file version
> > etc.) is already a bad disk usage pattern by itself. And NFS didn't
> > handle it better either ...
> > 
> > Anyway, nice to know that a specialized NAS device could help there.
> 
> Usually you are waiting on disk head motion - and if you run nfs in sync 
> mode you wait for completion on every write.  The things that can help 
> are lots of physical disks in the volume (better odds for the head to 
> already be near the right place) and running async with lots of 
> buffering.  Expensive devices might even have some battery-backed or 
> nonvolatile buffering.
> 

yep, the NAS head has a lot, lot of buffering that is battery backed so
the writes complete pretty quickly.

ski

-- 
"When we try to pick out anything by itself, we find it
 connected to the entire universe"            John Muir

Chris "Ski" Kacoroski, kacoroski AT gmail DOT com, 206-501-9803
or ski98033 on most IM services



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