On Thu, 2008-03-13 at 13:48 +0100, Brian J. Murrell wrote: > On Thu, 2008-03-13 at 12:59 +0100, Jakob Goldbach wrote: > > > > No need to freeze the filesystem while creating the snapshot to ensure a > > consistent filesystem on the snapshot ? > > I've been corrected about this before and maybe it will happen again, > but a) there is no need to freeze the filesystem and b) probably when > you mount the snapshot, the journal (which may contain transactions when > the snapshot is taken) will be replayed and then everything should be > good.
For taking snapshots the filesystem(or block device) must be frozen or the snapshots will not be consistent. LVM calls freeze_bdev() to lock a filesystem and bring it into a consistent state. It is not exported to userspace though and is currently uses only by device-mapper AFAIK. Thanks, Kalpak. > > > (xfs has a xfs_freeze function that does just this) > > Yeah. I don't know enough about xfs to understand why this is needed, > but probably the inconsistency of an "open" xfs filesystem is more > disastrous than an ext3 filesystem. > > b. > > > _______________________________________________ > Lustre-discuss mailing list > [email protected] > http://lists.lustre.org/mailman/listinfo/lustre-discuss _______________________________________________ Lustre-discuss mailing list [email protected] http://lists.lustre.org/mailman/listinfo/lustre-discuss
