[lxc-users] Issue upgrading from LXD apt to snap

[Sean McNamara]

Update:

The error about the DB schema from the apt version of lxd
(/usr/bin/lxd) was due to apt, for some reason, deciding to install
lxd *2.0.11* instead of the 2.21 I had been using from backports. I
forced the backport version and now both LXD daemons start
concurrently!

However, lxd.migrate doesn't complete cleanly. See below. I am using
ZFS for storage but I have no idea why it's trying to umount / !

# lxd.migrate
=> Connecting to source server
=> Connecting to destination server
=> Running sanity checks

=== Source server
LXD version: 2.21
LXD PID: 17828
Resources:
  Containers: 9
  Images: 3
  Networks: 1
  Storage pools: 1

=== Destination server
LXD version: 3.0.0
LXD PID: 3238
Resources:
  Containers: 0
  Images: 0
  Networks: 0
  Storage pools: 0

The migration process will shut down all your containers then move
your data to the destination LXD.
Once the data is moved, the destination LXD will start and apply any
needed updates.
And finally your containers will be brought back to their previous
state, completing the migration.

Are you ready to proceed (yes/no) [default=no]? yes
=> Shutting down the source LXD
=> Stopping the source LXD units
=> Stopping the destination LXD unit
=> Unmounting source LXD paths
=> Unmounting destination LXD paths
=> Wiping destination LXD clean
=> Moving the data
=> Moving the database
=> Backing up the database
=> Opening the database
=> Updating the storage backends
error: Failed to update the storage pools: Failed to run: zfs set
mountpoint=/var/lib/snapd/hostfs/ tank/root: umount: /: target is busy
        (In some cases useful info about processes that
         use the device is found by lsof(8) or fuser(1).)
cannot unmount '/': umount failed


Current state of my ZFS volumes:

# zfs list
NAME
                USED  AVAIL  REFER  MOUNTPOINT
tank
                556G  1.21T    19K  none
tank/containers
                182G  1.21T    19K  none
tank/containers/cont1
               18.9G  1.21T  18.1G
/var/snap/lxd/common/lxd/storage-pools/tank/containers/cont1
tank/containers/cont2
                 5.85G  1.21T  6.03G
/var/snap/lxd/common/lxd/storage-pools/tank/containers/cont2
tank/containers/cont3
             252M  1.21T   433M
/var/snap/lxd/common/lxd/storage-pools/tank/containers/cont3
tank/containers/cont4
               10.5G  1.21T  9.00G
/var/snap/lxd/common/lxd/storage-pools/tank/containers/cont4
#... etc (for several more containers)





On Wed, Apr 11, 2018 at 11:54 PM, Sean McNamara <smcnam at gmail.com> wrote:
> Hi,
>
> I'm on Ubuntu 16.04; the last working version of LXD I had was 2.21
> from backports.
>
> I wanted to upgrade to 3.0 but it isn't in the backports repo yet, it
> seems, so I went ahead and installed the snap. Then I removed the
> original package, perhaps not realizing until it was too late that I
> wasn't suppposed to do that.
>
> It seems the lxd.migrate command that you're *supposed* to run (which
> I wasn't aware of until recently) requires the original lxd server to
> be running -- that is, in my case, the one installed via apt. However,
> that one now won't start. It says:
>
> error: The database schema is more recent than LXD's schema.
>
> I wish the lxd binary had more flexibility and information about:
>
>  - How do I identify the directory where this lxd command is looking
> for its database/config files?
>  - How do I *tell it* to use a specific (non-default) directory for
> its database/config files?
>  - What environment variables should I check, if those are applicable?
>
> That info should go in `lxd --help`, IMO. As of now I'm stuck on this
> error. I assume I have a working LXD database in the normal /var
> location that somehow got updated to database schema for version 3.0,
> but I can't start *either* version of LXD now.
>
> When I try to start /usr/bin/lxd, I get the above error. When I try to
> start /snap/lxd/bin/lxd, it just hangs trying to connect:
>
> # /snap/lxd/current/bin/lxd -d
> DBUG[04-12|03:54:05] Connecting to a local LXD over a Unix socket
> DBUG[04-12|03:54:05] Sending request to LXD                   etag=
> method=GET url=http://unix.socket/1.0
>
> How can I salvage my original LXD config / containers in /var/lib/lxd
> and make it work with the snap?
>
> Thanks,
>
> Sean