Change default mountpoint/volume name for LXC container on ZFS storage

[onlime]

I have setup a ZFS local storage on latest ProxmoxVE 4.2 with the following options:

• ID: zfs-containers
• ZFS Pool: rpool/ROOT
• Content: Container

When creating a new LXC container via ProxmoxVE WebUI Create CT, it get's mounted and name as follows:

$ zfs list
NAME  USED  AVAIL  REFER  MOUNTPOINT
rpool  13.0G  436G  144K  /rpool
rpool/ROOT  5.41G  436G  112K  /rpool/ROOT
rpool/ROOT/pve-1  2.76G  436G  2.76G  /
rpool/ROOT/subvol-184-disk-1  482M  19.5G  482M  /rpool/ROOT/subvol-184-disk-1
rpool/swap  7.44G  444G  180K  -

I would like to change default ZFS volume name to pve-CTID instead of subvol-CTID-disk-1 and mountpoint to /var/lib/vz/private/CTID instead of /rpool/ROOT/subvol-CTID-disk-1, resulting in:

rpool/ROOT/pve-184  482M  19.5G  482M  /var/lib/vz/private/184

Can this be done in some global configuration? Where is the naming scheme defined?

 

[dietmar]

Can this be done in some global configuration? Where is the naming scheme defined?

I guess we hardcoded that naming scheme a several places, so it would be hard to change that. We also use disk names to encode some informations, so we cannot allow arbitrary name changes.

 

[LnxBil]

For the mountpoint problem, your should look at the mountpoint property for the parent pool. I don't know if it works fine with the proxmox ve logic as @dietmar described, but it works in "ordinary" ZFS.

Also, don't use ROOT als your mounted ZFS pool, create a new one e.g.

zfs create rpool/container

and use that one. The ROOT is normally used for different root-devices and is a kind of a special place.

 

[onlime]

Thanks @dietmar and @LnxBil for your great support. I will then stick with the hardcoded naming scheme.
Finally, I also found the right spot in the documentation:
https://pve.proxmox.com/wiki/Storage:_ZFS#Using_ZFS_Storage_Plugin_.28via_Proxmox_VE_GUI_or_shell.29

I followed this recommendation (hopefully this is best practice), creating the ZFS pool and storage:

$ zfs create rpool/zfsdisks
$ add zfspool zfsvols -pool rpool/zfsdisks -content images,rootdir -sparse

Final result:

$ zfs list
NAME  USED  AVAIL  REFER  MOUNTPOINT
rpool  13.0G  436G  144K  /rpool
rpool/ROOT  4.89G  436G  112K  /rpool/ROOT
rpool/ROOT/pve-1  2.76G  436G  2.76G  /
rpool/swap  7.44G  444G  180K  -
rpool/zfsdisks  560M  436G  96K  /rpool/zfsdisks
rpool/zfsdisks/subvol-184-disk-1  560M  436G  529M  /rpool/zfsdisks/subvol-184-disk-1

Wouldn't it make sense to mount the CT e.g. at /var/lib/lxc/subvol-184-disk-1 (next to /var/lib/lxc/184/rootfs)? - I am just used to the old OpenVZ way in ProxmoxVE 3.4. I'd like to make sure to follow your recommendations / best practice before migrating all containers to LXC.

 

[fabian]

"/var/lib/lxc" is where lxc expects its files/paths, so we only put stuff there that is expected (config file + container root mount point)