Extend ZFS zpool of Linux Ubuntu NextCloud VM

If you are running a virtual machine with NextCloud v16 on linux ubuntu and you want to extend /mnt/ncdata, then:

1. Make sure your backup is fine, think about creating a vm snapshot
2. Extend second virtual harddrive disk in VMWare virtual machine settings (e.g. from 40Gb to 170Gb)
3. Login using SSH/VMWare-Console, change to root user using sudo su or sudo -i
4. Check the zpool size using zpool list
5. Check the /mnt/ncdata size using df -h
6. Read the new partition size using parted -l with the answer "fix" for the adjustment
7. You can delete the buffer partition 9 using parted /dev/sdb rm 9
8. Extend the first partition using to 100% of the available size parted /dev/sdb resizepart 1 100%
9. Using zpool online -e ncdata /dev/sdb you can adjust the partition to the correct size
10. Check the new zpool size using zpool list
11. Check the new /mnt/ncdata size using df -h

Example with nextcloud 16 on Ubuntu 18.04:

root@nextcloud:/mnt# zpool list
NAME     SIZE  ALLOC   FREE  EXPANDSZ   FRAG    CAP  DEDUP  HEALTH  ALTROOT
ncdata  39.8G  15.2M  39.7G         -     0%     0%  1.00x  ONLINE  - 
root@nextcloud:/mnt#
root@nextcloud:/mnt#
root@nextcloud:/mnt# df -Th
Filesystem                     Type      Size  Used Avail Use% Mounted on
[...]
ncdata                         zfs        39G  896K   39G   1% /mnt/ncdata
[...]
root@nextcloud:/mnt#
root@nextcloud:/mnt# parted -l
[...]
Model: VMware Virtual disk (scsi)
Disk /dev/sdb: 183GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags:

Number  Start   End     Size    File system  Name                  Flags
 1      1049kB  42.9GB  42.9GB  zfs          zfs-28cd7
 9      42.9GB  42.9GB  8389kB[...]
root@nextcloud:/mnt#
root@nextcloud:/mnt#
root@nextcloud:/mnt# parted /dev/sdb rm 9
Information: You may need to update /etc/fstab.
root@nextcloud:/mnt#
root@nextcloud:/mnt# parted /dev/sdb resizepart 1 100%
Information: You may need to update /etc/fstab.
root@nextcloud:/mnt#
root@nextcloud:/mnt# zpool online -e ncdata /dev/sdb
root@nextcloud:/mnt#
root@nextcloud:/mnt# zpool list
NAME     SIZE  ALLOC   FREE  EXPANDSZ   FRAG    CAP  DEDUP  HEALTH  ALTROOT
ncdata   170G  2.51M   170G         -     0%     0%  1.00x  ONLINE  -
root@nextcloud:/mnt#
root@nextcloud:/mnt# df -h
Filesystem                      Size  Used Avail Use% Mounted on[...]
ncdata                          165G  896K  165G   1% /mnt/ncdata[...]
root@nextcloud:/mnt#



Update 25.12.2020: If you are running Ubuntu 20/Nextcloud VM 20, then follow the instrutions here starting point 7: https://how2itsec.blogspot.com/2020/12/increase-disk-and-zfs-of-nextcloud-vm.html

Hint when VMWare doesnt show a snapshot

If VMWare ESXi/vCenter/your vSphere environment does not show a virtual machine snapshot, however it is there and the virtual machine is using it, here is a little trick which might help you:

1. Make sure you have some free space left in your datastore, in which the vm is stored.
2. Create another virtual machine snapshot 
3. Click on "delete all snapshots"

This can trigger the ESXi to delete all snapshots, including the one which isn't shown. However this does not always work, in which case working with a clone of the VM and vmkfstools can help.