From mboxrd@z Thu Jan 1 00:00:00 1970 From: Goffredo Baroncelli Subject: Re: btrfs-progs: New utility to swap subvolumes Date: Mon, 28 Dec 2009 20:08:31 +0100 Message-ID: <200912282008.31628.kreijack@libero.it> References: <4B32CF4D.90406@jp.fujitsu.com> <200912272123.37585.kreijack@alice.it> <4B380C22.4010809@jp.fujitsu.com> Mime-Version: 1.0 Content-Type: Text/Plain; charset="iso-2022-jp" Cc: linux-btrfs@vger.kernel.org To: TARUISI Hiroaki Return-path: In-Reply-To: <4B380C22.4010809@jp.fujitsu.com> List-ID: Hi Taruisi, On Monday 28 December 2009, TARUISI Hiroaki wrote: [...] > We can swap subvolumes regardless of mounted-subvolume. (only > when we mount other subvolume than fs tree) I resolved this kind of problem as described in my previous email ([RFC] proposal for a btrfs filesystem layout - 20/Nov/2009): I used a sub-volume as root of my system, but I mounted also the root of the btrfs filesystem for handling the sub-volumes under "/var/btrfs". It work quiet well: 1) I can swap the sub-volumes only with the mv commands 2) I can switch to an old snapshot of the root at boot time, because my scripts update the grub entries with the list of the valid snapshots 3) I can switch permanently two sub-volumes exchanging their names 4) I can remove a sub-volume quite easily > And, because we can identify snapshot (its date or target subvol) > with subvolume ID, it is suitable to swap with ID. Why you want to to identify a sub-volume with its id ? I like the idea to identify a sub-volumes with an identifier which is not file-system related. To me the fact that a sub-volume is identified with its "mount point" seems to me a limit instead that an advantage. But it seems that I am alone to thinking that :-( So I am curious about your reasons. BR Goffredo -- gpg key@ keyserver.linux.it: Goffredo Baroncelli (ghigo) Key fingerprint = 4769 7E51 5293 D36C 814E C054 BF04 F161 3DC5 0512