Chris Murphy wrote:
On Jan 30, 2014, at 6:02 PM, Jorge Fábregas <jorge.fabregas(a)gmail.com> wrote:
>
> #btrfs subvolume list /
> ID 257 gen 102 top level 5 path root
> ID 258 gen 102 top level 5 path home
> ID 278 gen 95 top level 257 path yum_20140130172422
FYI note the top level is 257 which is root subvolume, therefore this entry is
the same as saying "top level 5 path root/yum_20140130172422"
>
> # mount -o subvolid=5 /dev/vda3 /mnt
> # btrfs subvolume delete /mnt/root
> Delete subvolume '/mnt/root'
> ERROR: cannot delete '/mnt/root' - Device or resource busy
> I believe this is happening because the snapshots are being created
> WITHIN the subvolume they're snapshotting against.
Correct.
> Can you modify the yum plugin so that it places its
> snapshots within OTHER particular subvolume?
I think a bug should be filed. It's a bug/RFE.
Another option is to look at snapper. It uses a subvolume at the top level
called .snapper that it puts snapshots into. It's in the fedora repo.
> BTW, is there anyone out there using this plugin with btrfs?
I'm not, partly for the reason that I don't want snapshots available in the
normally mounted fs because I find it a bit confusing, and also because it
does as you say, it anchors root, boot, home subvolumes. Maybe I want to
delete them if I get a totally messed up update that's beyond repair or my
interest.
Do you know if these are read only snapshots?
btrfs sub show /home/yum_20140130172422
> p.d. I know snapshotting /home doesn't make sense at all for yum updates
> but I followed it along…
I'm not bothered by it but the purpose for snapshot-rollback of boot and root
vs home are different. Maybe for /home we'd want hourly snapshots. And we'd
probably never rollback /home for a bad system update. We'd keep existing
home, and all of its changes since updating. And then just rollback boot and
root.
And on devel@ this was discussed that perhaps finer granularity is needed than
what we presently have. For example I have an additional subvolume called
journald at the top level which fstab mounts as:
UUID=xxx /var/log/journal btrfs subvol=journald,compress=lzo,ssd
This is because for now I've decided I don't want snapshots having their own
independent journal. I want a "master" journal kept up to date regardless of
what snapshot I boot. But it may turn out this is not a good idea since the
journal entries don't necessarily indicate what snapshot I've booted.
Chris Murphy
I filed this BR:
https://bugzilla.redhat.com/show_bug.cgi?id=1060241