[SOLVED] Cannt get snapshot branches: TASK ERROR: can't rollback, ____ is not most recent snapshot

[jsalas424]

I'm running PVE 6.3-3 and am trying to get snapshots as branches are per the documention: https://pve.proxmox.com/wiki/File:Screen-vm-snapshots.png

I can't seem to get anything besides sequential snapshots, what am I doing wrong here? This disk and the snapshots are saved to a zfspool managed by proxmox.



I also cannot rollback to an earlier snapshot and then diverge off to make a new tree. I can only select the most recent snapshot.

I'm running PVE 6.3-3 and am trying to get snapshots as branches are per the documention: https://pve.proxmox.com/wiki/File:Screen-vm-snapshots.png

 

[aaron]

Snapshots depend heavily on the underlying storage. qcow2 files can do the mentioned branching of snapshots. If you use LVM thin or ZFS you are out of luck as these storages only support linear snapshots.

 

[jsalas424]

Thanks for the reply Aaron, I migrated disk from zfspool to the corresponding directory I have mounted there and converted to qcow2. Problem solved.

 

[hivebof832]

Sorry to revive an old thread, but I have the still same problem with PVE7.
Why do I need to create a directory and move everything there? Why doesn't it work directly with ZFS pools?

 

[fabian]

because ZFS doesn't allow rollback to anything other than the most recent snapshot

 

[hivebof832]

So what's the difference when I create a folder on ZFS? Then PVE doesn't use ZFS snapshots but creates own snapshots?

 

[fabian]

if you use a directory storage (backed by whatever ) you can use qcow2 image files for VMs (not available for containers though). those support snapshots directly stored in the image file(s), and rollback to arbitrary snapshots.

 

[utkonos]

Sorry to keep bumping this old thread as well. I just wanted to make a post here that makes it crystal clear, step by step how to get to where people want to go. It was not immediately clear from the above exactly how this all should work (this is my fault, not anyone on this thread). Lastly, the following works for me, so if I am wrong in some way, please correct me.

On a freshly installed 7.2 on zfs, there are two types of storage:

local (directory) which contains: Container template, VZDump backup file, ISO image
local-zfs (zfs) which contains: Disk image, Container
On this fresh install with no VMs created, local-zfs is empty.

Navigate using the Server View in the upper left: Datacenter -> Storage
Select local-zfs -> Click "Remove" button -> Click "Yes" button
Click "Add" button -> Select "Directory"
In the Add Directory dialog box:
ID: local-zfs
Directory: /var/lib/vz
Content: Disk image
Nodes: <SelectNameOfYourNode>
Enable: Checked
Shared: Unchecked
Preallocation: Default

Now the original zfs storage that does not allow non-linear snapshots has been replaced by a zfs-backed directory storage of the same name. From this point on, VMs that I create on this storage can take non-linear snapshots as expected. I don't use containers, so I have omitted Container from the content list for this storage.

NOTE: Changing to ZFS backed Directory storage requires that the volume format be explicitly specified as "qcow2" if using the API. The API default is "raw" which does not support snapshots on this type of storage. The GUI default is unchanged from being qcow2 in all cases.

Again, sorry for bumping this thread, but I benefit from precise instructions, so I hope this helps other people. And if there are any errors at all in the above, please let me know and I can correct it.

 

[utkonos]

NOTE: I have also found that a fresh install on ext4 results in local (directory) and local-lvm (LVM-Thin). Right out of the box, when one creates VMs, they are disk type raw, and it supports non-linear snapshots. From what I can tell, only zfs without a Directory type storage cannot support non-linear snapshots. In a post above, zfs was listed with LVM-thin as not supporting, but from my testing it does. Did something change?

 

[fabian]

I think that was a mistake - AFAIR LVM thin always supported rolling back to arbitrary snapshots.

 

[utkonos]

I think that was a mistake - AFAIR LVM thin always supported rolling back to arbitrary snapshots.

No problem at all! I wanted to memorialize that here in the thread if people hit this issue in the future.

Thanks for your help!

 

[why-be-banned]

I heard that ZFS is an excellent system, so I spent a few days reinstalling Proxmox with ZFS and migrating data, and then I encountered the same problem as you. This is an intolerable issue, so now I have to spend a few more days to revert Proxmox back to the original LVM.