On Tue, Jul 08, 2008 at 11:55:02PM -0700, Arjan van de Ven wrote: > On Wed, 09 Jul 2008 08:48:42 +0200 > Miklos Szeredi <miklos@xxxxxxxxxx> wrote: > > > On Tue, 8 Jul 2008, Arjan van de Ven wrote: > > > nah he needs to do > > > > > > make_snapshot ; backup-command ; unref_snapshot. > > > > > > freezing isn't the right solution for the backup problem ;) > > > > Confused, what's freezing _is_ for then? Patch description says: > > > > Currently, ext3 in mainline Linux doesn't have the freeze feature > > which suspends write requests. So, we cannot take a backup which > > keeps the filesystem's consistency with the storage device's features > > (snapshot and replication) while it is mounted. > > I tihnk the idea there is > > freeze . do the snapshot op . unfreeze . make backup of snapshot > > one can argue about the need of doing the first 3 steps via a userland > loop; it sure sounds like one needs to be really careful to not do any > writes to the fs from the app that does snapshots (and that includes > doing any syscalls in the kernel that allocate memory.. just because > that already could cause unrelated data to be written from inside the > app. Not fun.) Bloody hell! Doesn't *anyone* understand that a frozen filesystem is *clean*? That the process of freezing it ensures all dirty data and metadata is written out before the freeze completes? And that once frozen, it can't be dirtied until unfrozen? That's 3 (or is it 4 - maybe 5 now that I think about it) different ppl in 24 hours that have made this same broken argument about being unable to write back dirty data on a frozen filesystem...... Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
