Hi All,
Setup
Distribution: Ubuntu server
Distribution version: 18.04
kernel_version: 5.3.0-59-generic
LXD version: 4.0.2 LTS
Hardware : 1 disk for OS / 1 disk with a dedicated zfs pool
I did some research :
I’m wondering in case of a disk failure (OS) would it be possible to reinstall LXD and attach the existing pool to the new LXD ?
From my understanding it’s not and I will have to follow the “back process” .
Is it right ?
Thx !
I am a bit confused.
If you have a disk failure, your pool would be lost.
Or are you referring to a scenario in which the pool is on a different drive than the LXD configuration?
In this case (pool instact) simos guide should apply to a new installation (or re-installation) of LXD as well. because in all cases you have an empty LXD configuration.
Or are you referring to a scenario in which the pool is on a different drive than the LXD configuration?
Sorry, yes I’m referring to this scenario !
I have 2 physical drives :
If I lose “sda” and I have to reinstall system+LXD, would it be possible to attach my existing zfs pool ? (populated)
As I understand Simos still have access to his LXD configuration.
I think simos is describing exactly that scenario:
But disaster strucks, and LXD loses its database and forgets about your containers. Your data is there in the ZFS pool, but LXD has forgotten them because its configuration (database) has been lost.
In this post we see how to recover our containers when the LXD database is, for some reason, gone.
Note: To clarify all LXD configuration is saved in the database.
So if it’s lost, the configuration is also lost.
So the answer is yes.
Let’s do it now. Create a VM, install LXD and use ZFS for the storage pool. Create a few containers. Remove LXD, install LXD, reconnect to storage pool.
I will be using the deb package of LXD for brevity. Adapt to match your use-case.
$ lxc launch ubuntu:18.04 vm1 --vm --profile default --profile vm
Creating vm1
Starting vm1
$ # wait for the VM to bootup, to install LXD agent, then reboot, then be ready to connect with `lxc exec`.
$ lxc shell vm1
ubuntu@vm1:~$ sudo apt update
ubuntu@vm1:~$ sudo apt install -y zfsutils-linux
ubuntu@vm1:~$ lxd init
Would you like to use LXD clustering? (yes/no) [default=no]:
Do you want to configure a new storage pool? (yes/no) [default=yes]:
Name of the new storage pool [default=default]:
Name of the storage backend to use (btrfs, dir, lvm, zfs) [default=zfs]:
Create a new ZFS pool? (yes/no) [default=yes]:
Would you like to use an existing block device? (yes/no) [default=no]:
Size in GB of the new loop device (1GB minimum) [default=15GB]:
Would you like to connect to a MAAS server? (yes/no) [default=no]:
Would you like to create a new local network bridge? (yes/no) [default=yes]:
What should the new bridge be called? [default=lxdbr0]:
What IPv4 address should be used? (CIDR subnet notation, “auto” or “none”) [default=auto]:
What IPv6 address should be used? (CIDR subnet notation, “auto” or “none”) [default=auto]:
Would you like LXD to be available over the network? (yes/no) [default=no]:
Would you like stale cached images to be updated automatically? (yes/no) [default=yes]
Would you like a YAML "lxd init" preseed to be printed? (yes/no) [default=no]:
ubuntu@vm1:~$ lxc launch ubuntu:18.04 mycontainer1
To start your first container, try: lxc launch ubuntu:18.04
Creating mycontainer1
Starting mycontainer1
ubuntu@vm1:~$ lxc launch ubuntu:20.04 mycontainer2
Creating mycontainer2
Starting mycontainer2
ubuntu@vm1:~$ lxc list -c ns4
+--------------+---------+-----------------------+
| NAME | STATE | IPV4 |
+--------------+---------+-----------------------+
| mycontainer1 | RUNNING | 10.182.107.158 (eth0) |
+--------------+---------+-----------------------+
| mycontainer2 | RUNNING | 10.182.107.180 (eth0) |
+--------------+---------+-----------------------+
ubuntu@vm1:~$ sudo apt remove --purge lxd -y
ubuntu@vm1:~$ sudo zfs list
... # shows output, ZFS storage pool is there.
ubuntu@vm1:~$ sudo apt install lxd
ubuntu@vm1:~$ lxc list
+------+-------+------+------+------+-----------+
| NAME | STATE | IPV4 | IPV6 | TYPE | SNAPSHOTS |
+------+-------+------+------+------+-----------+
ubuntu@vm1:~$ sudo zfs list
NAME USED AVAIL REFER MOUNTPOINT
default 885M 12.6G 24K none
default/containers 16.3M 12.6G 24K none
default/containers/mycontainer1 7.33M 12.6G 344M /var/lib/lxd/storage-pools/default/containers/mycontainer1
default/containers/mycontainer2 8.91M 12.6G 527M /var/lib/lxd/storage-pools/default/containers/mycontainer2
default/custom 24K 12.6G 24K none
default/deleted 24K 12.6G 24K none
default/images 868M 12.6G 24K none
default/images/aa623d1c9562bd954dc4c685a54eacac3e0ceacf7a05a7308de0d1aed3a8996a 525M 12.6G 525M none
default/images/c8d9c12f5a4448d3cdd4f98f994c587272fbeba249390af0f21eeef69a05cb07 343M 12.6G 343M none
default/snapshots 24K 12.6G 24K none
ubuntu@vm1:~$ sudo zfs mount default/containers/mycontainer1
ubuntu@vm1:~$ sudo zfs mount default/containers/mycontainer2
ubuntu@vm1:~$ sudo lxd import mycontainer1
ubuntu@vm1:~$ sudo lxd import mycontainer2
ubuntu@vm1:~$ lxc profile list
+---------+---------+
| NAME | USED BY |
+---------+---------+
| default | 2 |
+---------+---------+
ubuntu@vm1:~$ lxc profile show default
config: {}
description: Default LXD profile
devices: {}
name: default
used_by:
- /1.0/containers/mycontainer1
- /1.0/containers/mycontainer2
ubuntu@vm1:~$ lxc network list
+--------+----------+---------+-------------+---------+
| NAME | TYPE | MANAGED | DESCRIPTION | USED BY |
+--------+----------+---------+-------------+---------+
| enp5s0 | physical | NO | | 0 |
+--------+----------+---------+-------------+---------+
ubuntu@vm1:~$ lxc network create lxdbr0
Network lxdbr0 created
ubuntu@vm1:~$ lxc profile device add default eth0 nic name=eth0 nictype=bridged parent=enp5s0
Device eth0 added to default
ubuntu@vm1:~$ lxc profile device add default root disk path=/ pool=default
Device root added to default
ubuntu@vm1:~$ lxc profile show default
config: {}
description: Default LXD profile
devices:
eth0:
name: eth0
nictype: bridged
parent: enp5s0
type: nic
root:
path: /
pool: default
type: disk
name: default
used_by:
- /1.0/containers/mycontainer1
- /1.0/containers/mycontainer2
ubuntu@vm1:~$
At this stage, you should just be able to start the containers and they should work.
I tried this exactly as above and I could not start the containers. They were failing on a networking issue; LXD was trying to setup Openvswitch and failing. Although there was no such configuration in the first place. I am not sure what went wrong, and whether this is an issue fixed in newer versions of LXD. You can give it a go yourself, and report back.
Thank very much Simos !
I will test with LXD latest release and report back here