Re: btrfs-progs: New utility to swap subvolumes

Goffredo Baroncelli
2009-12-28T19:08:31Z

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

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gpg key@ keyserver.linux.it: Goffredo Baroncelli (ghigo) <kreijackATinwind.it>