Attempt to cp an existing VM results in error

bmullan · May 1, 2024, 12:43am

I have an existing LXD VM called “win11”.
Recently I had NO problem making a copy named “win11-demo”

I’d deleted the VM “win11-demo” a few days ago but now if I try to re-create it
using "$ lxc cp win11 win11-demo it now fails?

See below…

$ lxc ls
±-----------------±--------------±--------±-------±-----------------------------±-------------------+
| NAME | STATE | IPV4 | IPV6 | TYPE | SNAPSHOTS |
±-----------------±--------------±--------±-------±-----------------------------±------------------+
| ubuntu-vm | STOPPED | | | VIRTUAL-MACHINE | 0 |
±-----------------±--------------±--------±-------±-----------------------------±------------------+
| win11 | STOPPED | | | VIRTUAL-MACHINE | 0 |
±-----------------±--------------±--------±-------±-----------------------------±------------------+

$ lxc cp win11 win11-demo
Error: Create instance from copy: Cannot create volume, already exists on target storage

Any suggestion on how to fix this?

The $ lxc ls no longer lists “win11-demo” (see above) so why this error above?

thanks for any hints on how to resolve

tomp · May 1, 2024, 8:19am

The error suggests that the storage volume on the disk itself is still present.

What storage driver are you using?

bmullan · May 1, 2024, 9:41am

All the drives on this machine are BTRFS

tomp · May 1, 2024, 9:42am

What does this show:

ls /var/snap/lxd/common/lxd/storage-pools/<pool>/virtual-machines -la

bmullan · May 1, 2024, 9:52am

That directory is “empty”

$ sudo su
ls -la /var/snap/lxd/common/lxd/storage-pools/lxd-storage-pool
drwx–x–x 1 root root 0 Mar 25 09:25 .
drwx–x–x 1 root root 32 Mar 25 09:25 …

And I do have 2 VMs currently stopped that are on that pool…

# lxc ls
±----------±--------±-----±-----±----------------±----------+
| NAME | STATE | IPV4 | IPV6 | TYPE | SNAPSHOTS |
±----------±--------±-----±-----±----------------±----------+
| ubuntu-vm | STOPPED | | | VIRTUAL-MACHINE | 0 |
±----------±--------±-----±-----±----------------±----------+
| win11 | STOPPED | | | VIRTUAL-MACHINE | 0 |
±----------±--------±-----±-----±----------------±----------+

tomp · May 1, 2024, 9:55am

Try this:

sudo nsenter --mount=/run/snapd/ns/lxd.mnt -- ls -la /var/snap/lxd/common/lxd/storage-pools/lxd-storage-pool

bmullan · May 1, 2024, 10:17am

# sudo nsenter --mount=/run/snapd/ns/lxd.mnt – ls -la /var/snap/lxd/common/lxd/storage-pools/lxd-storage-pool

total 16
drwxr-xr-x 1 root root 214 Mar 25 09:25 .
drwx–x–x 1 root root 32 Mar 25 09:25 …
drwx–x–x 1 root root 0 Mar 25 09:25 buckets
drwx–x–x 1 root root 36 Apr 30 19:41 containers
drwx–x–x 1 root root 0 Mar 25 09:25 containers-snapshots
drwx–x–x 1 root root 0 Mar 25 09:25 custom
drwx–x–x 1 root root 0 Mar 25 09:25 custom-snapshots
drwx–x–x 1 root root 512 Apr 30 19:37 images
drwx–x–x 1 root root 60 Apr 30 20:28 virtual-machines
drwx–x–x 1 root root 0 Mar 26 10:58 virtual-machines-snapshots

tomp · May 1, 2024, 10:18am

We need to see inside the virtual-machines directory.

sudo nsenter --mount=/run/snapd/ns/lxd.mnt – ls -la /var/snap/lxd/common/lxd/storage-pools/lxd-storage-pool/virtual-machines

bmullan · May 1, 2024, 10:50am

Sorry Tom, (its pretty early here)
I was entering your previous commands verbatum but on this machine lxd snap is installed on Ubuntu 22.04 on - /dev/nvme0n1p4

but using…

$ lxd init

the “lxd-storage-pool” was configured on /dev/sda1 mounted on /mnt/lxd-storage-pool

So rerunning:

# ls /mnt/lxd-storage-pool/virtual-machines -la
total 16
drwx–x–x 1 root root 60 Apr 30 20:28 .
drwxr-xr-x 1 root root 214 Mar 25 09:25 …
d–x------ 1 root root 252 Apr 4 10:10 ubuntu
d–x------ 1 root root 252 Mar 25 09:40 ubuntu-vm
d–x------ 1 root root 234 Mar 25 09:30 win11
d–x------ 1 root root 234 Mar 25 09:30 win11-demo

The above does still show a win11-demo directory

/mnt/lxd-storage-pool/virtual-machines/win11-demo# ls -la
total 20326064
d–x------ 1 root root 234 Mar 25 09:30 .
drwx–x–x 1 root root 60 Apr 30 20:28 …
-rw-r–r-- 1 root root 656 Mar 25 09:30 agent-client.crt
-rw------- 1 root root 288 Mar 25 09:30 agent-client.key
-rw-r–r-- 1 root root 688 Mar 25 09:30 agent.crt
-rw------- 1 root root 288 Mar 25 09:30 agent.key
-r-------- 1 root root 2219 Apr 17 16:34 backup.yaml
dr-x------ 1 lxd root 188 Apr 17 16:34 config
-rw-r–r-- 1 root root 91 Mar 23 22:02 metadata.yaml
-rw------- 1 lxd root 540672 Apr 17 16:34 OVMF_VARS.4MB.ms.fd
lrwxrwxrwx 1 root root 19 Mar 25 09:30 qemu.nvram → OVMF_VARS.4MB.ms.fd
-rw-r–r-- 1 root root 59055800320 Apr 17 16:34 root.img

tomp · May 1, 2024, 10:52am

OK so its still there indeed. We needed to switch into the LXD snap’s mount namespace to see it because its mounted there from /mnt/lxd-storage-pool/.

Suggest trying to removing it and then copying again.

bmullan · May 1, 2024, 10:53am

Thanks…
Yes, that fixed it.

But makes me wonder why that directory wasn’t deleted when I originally deleted the win11-demo vm?

tomp · May 1, 2024, 10:57am

I’m not sure what happened. If you can get a reproducer and log a bug we can hopefully prevent it happening in the future.