Alasdair, Thanks for the tips. Do you think it's possible DM's snapshots could've caused this corruption, or do you think the problem lies elsewhere? Alex On Mon, 21 Feb 2005 15:18:52 +0000, Alasdair G Kergon <agk@xxxxxxxxxx> wrote: > On Sun, Feb 20, 2005 at 11:25:37PM -0600, Alex Adriaanse wrote: > > This morning was the first time my backup script took > > a snapshot since upgrading to 2.6.10-ac12 (yesterday I had taken a few > > snapshots myself for testing purposes, this seemed to work fine). > > a) Activating a snapshot requires a lot of memory; > > b) If a snapshot can't get the memory it needs you have to back it > out manually (using dmsetup - some combination of resume, remove & > possibly reload) to avoid locking up the volume - what you have to do > depends how far it got before it failed; > > c) You should be OK once a snapshot is active and its origin has > successfully had a block written to it. > > Work is underway to address the various problems with snapshot activation > - we think we understand them all - but until the fixes have worked their > way through, unless you've enough memory in the machine it's best to avoid > them. > > Suggestions: > Only do one snapshot+backup at once; > Make sure logging in as root and using dmsetup does not depend on access > to anything in /var or /home (similar to the case of hard NFS mounts with > the server down) so you can still log in; > > BTW Also never snapshot the root filesystem unless you've mounted it noatime > or disabled hotplug etc. - e.g. the machine can lock up attempting to > update the atime on /sbin/hotplug while writes to the filesystem are blocked > > Alasdair > -- > agk@xxxxxxxxxx >
