Cannot backup to directory mounted at zfs filesystem

[jsalas424]

PVE 6.3-3
I created zfspool "NC.VM.Backups.zfspool" under the parent zfspool "Nextcloud.Storage". I then tried to mount a directory at that site, but cannot select it as a backup target.

INFO: starting new backup job: vzdump 69420 --remove 0 --mode snapshot --node TracheServ --compress zstd --storage NC.VM.Backups.dir
command 'df -P -T -B 1 /Nextcloud.Storage/NC.VM.Backups/dump' failed: exit code 1
ERROR: Backup of VM 69420 failed - unable to create temporary directory '/Nextcloud.Storage/NC.VM.Backups/dump/vzdump-qemu-1234-2020_12_27-22_26_07.tmp' at /usr/share/perl5/PVE/VZDump.pm line 816.
INFO: Failed at 2020-12-27 22:26:07
INFO: Backup job finished with errors
TASK ERROR: job errors

Storage config for the parent pool, sub-pool, and directory:

root@TracheServ:~# cat /etc/pve/storage.cfg
zfspool: Nextcloud.Storage
pool Nextcloud.Storage
content images,rootdir
mountpoint /Nextcloud.Storage
sparse 0

dir: NC.VM.Backups.dir
path /Nextcloud.Storage/NC.VM.Backups
content vztmpl,images,backup,snippets,iso,rootdir
is_mountpoint 1
mkdir 0
prune-backups keep-last=4
shared 0

zfspool: NC.VM.Backups.zfspool
pool Nextcloud.Storage/NC.VM.Backups
content images,rootdir
mountpoint /Nextcloud.Storage/NC.VM.Backups
sparse 0

The directory path exists and I can store things on the corresponding zfspool:

root@TracheServ:~# zfs list
NAME                                                                  USED  AVAIL     REFER  MOUNTPOINT
Nextcloud.Storage                                                     973G  1.68T      764G  /Nextcloud.Storage
Nextcloud.Storage/NC.VM.Backups                                      76.2G  1.68T       96K  /Nextcloud.Storage/NC.VM.Backups
Nextcloud.Storage/NC.VM.Backups/vm-201-state-Baseline                2.57G  1.69T      605M  -

 

[fabian]

please remove the mkdir 0 part..

 

[jsalas424]

please remove the mkdir 0 part..

I was under the impression that the is_mountpoint 1 and mkdir 0 are necessary for making a directory at a zfspool.

Here's what Aaron from your team told me in a separate discussion: https://forum.proxmox.com/threads/w...-much-space-on-local.78967/page-2#post-353015

"If you have a directory storage that is located right at a mount point, you need to configure the following two parameters for that storage:

Code:  
is_mountpoint 1
mkdir 0

"

 

[fabian]

is_mountpoint alone is sufficient (it will prevent activation of the storage until something is mounted at path). mkdir was the predecessor that just allowed to skip the directory creation to prevent "unable to mount over non-empty directory" situations, but it turned out that this was not sufficient so is_mountpoint was introduced.

 

[jsalas424]

is_mountpoint alone is sufficient (it will prevent activation of the storage until something is mounted at path). mkdir was the predecessor that just allowed to skip the directory creation to prevent "unable to mount over non-empty directory" situations, but it turned out that this was not sufficient so is_mountpoint was introduced.

That worked, thanks! So should I go and remove my mkdir flags from my other directories as well and just leave is_mountpoint?

INFO: starting new backup job: vzdump 400 --node TracheServ --mode snapshot --remove 0 --storage NC.VM.Backups.dir --compress zstd
INFO: Starting Backup of VM 400 (qemu)
INFO: Backup started at 2020-12-30 10:01:01
INFO: status = stopped
INFO: backup mode: stop
INFO: ionice priority: 7
INFO: VM Name: RStudio.Server
INFO: include disk 'scsi0' 'new_ssd.VMs:vm-400-disk-0' 50G
INFO: include disk 'scsi2' 'new_ssd.VMs:vm-400-disk-1' 20G
INFO: snapshots found (not included into backup)
INFO: creating vzdump archive '/Nextcloud.Storage/NC.VM.Backups/dump/vzdump-qemu-400-2020_12_30-10_01_01.vma.zst'
INFO: starting kvm to execute backup task
INFO: started backup task 'd855b857-ffe5-43b0-b89b-21457ea35778'