On Mon, Jun 11, 2012 at 01:18:17PM -0400, Greg Troxel wrote: > > Thor Lancelot Simon <[email protected]> writes: > > > On Mon, Jun 11, 2012 at 05:52:27PM +0200, Edgar Fu? wrote: > >> > Yes, but I have to question whether and why it would improve performance > >> > in this case. The stream of atime updates is still happening on the > >> > underlying filesystem, and that is still where you will be doing almost > >> > all of your reads from. > >> > >> My intent was to mount the snapshot ro,noatime and operate on that. > >> Am I again missing something stupid? > > You should only need ro; it doesn't make sense to talk about atime > updates or not when you aren't writing to the underlying block device. > > > Hm. No, I don't think so. I wonder -- will the snapshot management code > > cause the resulting snapshot to be in a consistent state so access through > > the filesystem is safe? > > I would say that it should or it's a bug; it seems the whole point of > snapshots is to get a consistent view of a filesystem. > Given that the normal use case seems to be things like > snapshot/dump/drop-snapshot, I would think that if it were buggy there's > a decent chance there would have been complaints by now.
You can test with fsck_ffs -X; I use it from daily scripts on some systems, and it does the job. -- Manuel Bouyer <[email protected]> NetBSD: 26 ans d'experience feront toujours la difference --
