On Jun 11, 2012, at 8:25 PM, Manuel Bouyer wrote: > On Mon, Jun 11, 2012 at 01:18:17PM -0400, Greg Troxel wrote: >> >> Thor Lancelot Simon <t...@panix.com> 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.
Or better with `fsck_ffs -x /snapshot/backup' to use a file system external snapshot. > -- > Manuel Bouyer <bou...@antioche.eu.org> > NetBSD: 26 ans d'experience feront toujours la difference > -- -- Juergen Hannken-Illjes - hann...@eis.cs.tu-bs.de - TU Braunschweig (Germany)