"Jeffrey J. Kosowsky" <email@example.com>
wrote on 02/23/2011 10:46:54 AM:
> Are you using lvm snapshots?
> It seems that some of my terribly slow recent performance has been
> to having lvm snapshots. I saw a site that claimed lvm snapshots in
> practice can degrade write performance up to 20-30x...
This is mostly true when your log file is on the same
spindle as the LV you're snapshotting. That should be considered
an absolute no-no. You get the type of performance dropoff you're
talking about. LVM snapshots pretty much require a dedicated drive
for the log. Or drives: if the volume you're snapshotting is
a, say, 6-disk RAID array, and you give only a single drive for the log,
everything gets bottlenecked by the log drive.