From mboxrd@z Thu Jan 1 00:00:00 1970 From: Lubos Kolouch Subject: Re: snapshot strange behaviour Date: Sun, 23 Jan 2011 20:06:10 +0000 (UTC) Message-ID: References: <4D3C1C49.8040104@libero.it> <4D3C6D23.106@libero.it> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 To: linux-btrfs@vger.kernel.org Return-path: List-ID: Goffredo Baroncelli, Sun, 23 Jan 2011 19:02:11 +0100: > On 01/23/2011 04:05 PM, Lubos Kolouch wrote: >> Goffredo Baroncelli, Sun, 23 Jan 2011 13:17:13 +0100: >> >>> Hi Lubos, >>> >>> On 01/23/2011 08:17 AM, Lubos Kolouch wrote: >>>> Hello, > >>>> Is this a bug or intended behaviour and I am missing something >>>> something? How to snapshot a subvolume, containing another >>>> subvolumes? >>> >>> It is the intended behavior. The snapshotting is not recursive about >>> subvolumes. If you snapshot a subvolume which contains another one, >>> you got only the content of the first subvolume. The directory "x/b" >>> which you see, is not the subvolume "b" snapshotted, but only the >>> "mount-point" of "b". >>> >>> >> Hi Goffredo, >> >> I understand. But then I think btrfs should refuse to do it or at least >> print a warning. Otherwise it is very inconvenient for the user, having >> to search for any subvolumes down the tree... > > > Sorry, but I can't agree. To me it seems a reasonable default. There are > a lot of cases where I would not snapshot a sub-sub-subvolume: my rootfs > is a subvolume, my home is in another one. I can snapshot, update the > root fs, then if something goes wrong I can roolback to the old one, > without affecting my home. > > This behavior is strictly related to the btrfs internal. > > Any way it is true that this behavior should be highlighted in the > documentation. > > And more, it is possible to add a "-R" flag to snapshot recursively a > subvolume... > > Goffredo The -R would be nice... two use cases : 1) directory many_small_files under the /home subvolume, that you need only for a while - it is easier to for example delete it when it is subvolume as well 2) backups subvolume backups -> subvolumes 20110122, 20110123, ... you want to delete backups older than x years -> it is much faster to do if it is a subvolume as well. But - you may as well want to be able snapshot or delete the whole backups subvolume. Lubos