Snapshot

[tdyboc]

Hi. Recently new to Proxmox and I have a question about snapshots, of a VM. My VM/CT storage is ZFS.

Been working with snapshots and initially stumbled upon this link, the screen capture is old as it reflects v2.3-1 and I'm running 6.3-2: https://pve.proxmox.com/wiki/File:Screen-vm-snapshots.png

In the above link/screen-cap, it appears that you can take multiple snapshots and nest them somehow as they appear that you can hierarchy them as well as collapse/expand the ones taken and possibly rollback to any of them.

Is this really possible? I can't seem to duplicate, operationally, what the link/screen-cap depicts. I have taken (4) snapshots but can't rollback to the oldest or topmost in my list.

Thanks.

 

[Dunuin]

It is possible to fork that snapshot tree. For example by cloning from a snapshot but I think you can't do that using the GUI.
But you should be able to rollback to any of your snapshots including the first one (loosing the newer snapshots).

 

[fiona]

Hi,
@tdyboc it actually depends on the kind of disks used. For ZFS you can only roll back to the most recent one (otherwise you would lose the newer ones, so PVE doesn't allow it), but for qcow2 disks you can roll back to wherever.

@Dunuin you should be able to select the snapshot when using clone in the GUI.

 

[tdyboc]

Thanks for the replies. Did additional reading, doesn't seem to explain things like i'd expect however I managed to figure it out and understand a bit better.
I have a single system with an SSD on which Proxmox is installed and also in that system are (2) SATA adapters one controls a bluray device and a RDX device i use for backups and the other one has 16 SATA drives which is my ZFS pool.
I don't plan to have anything on this system that I can't lose, it's just for me to 'puttz' with so i now created a ZFS dataset, in Proxmox added it as a directory for disk/container images and now I utilize QCOW2 rather than raw so I'm able to have different snapshots that I can roll to/from.

 

[Dunuin]

I don't know if that is a good solution. Now you are running a CoW filesystem (qcow2) ontop of a CoW filesystem (ZFS). That shouldn't be very efficient.

 

[jchwsu86]

Thanks for the replies. Did additional reading, doesn't seem to explain things like i'd expect however I managed to figure it out and understand a bit better.
I have a single system with an SSD on which Proxmox is installed and also in that system are (2) SATA adapters one controls a bluray device and a RDX device i use for backups and the other one has 16 SATA drives which is my ZFS pool.
I don't plan to have anything on this system that I can't lose, it's just for me to 'puttz' with so i now created a ZFS dataset, in Proxmox added it as a directory for disk/container images and now I utilize QCOW2 rather than raw so I'm able to have different snapshots that I can roll to/from.

How were you able to take snap shots on ZFS? For my testing setup, I am currently running ProxMox on a separate drive and then a single SSD for my vms. I have tried LVM, LVM-Thin, ZFS (single drive) and cannot use the snapshot feature, because my vms are forced to using raw.

 

[fiona]

Hi,

How were you able to take snap shots on ZFS? For my testing setup, I am currently running ProxMox on a separate drive and then a single SSD for my vms. I have tried LVM, LVM-Thin, ZFS (single drive) and cannot use the snapshot feature, because my vms are forced to using raw.

to make snapshots all virtual disks need to be on storages that support snapshots and you can't have passthrough disks. Could you share a VM configuration where you cannot take a snapshot?

 

[jchwsu86]

Hi,

to make snapshots all virtual disks need to be on storages that support snapshots and you can't have passthrough disks. Could you share a VM configuration where you cannot take a snapshot?

Wow - I guess my mind wasn't in the right place when I was testing this.

Before I started, my VM was in an LVM.

• I went to snap shots and was told I couldn't make one.
• I then went to hardware and tried to move the disk > To the same LVM > But I could not convert to qcow (in the same LVM)

I went ahead and blew away the LVM it was running on and setup an LVM-Thin.

• Now I went back to hardware to move the disk > To the same LVM-Thin, but couldn't convert to qcow2
• I then went to snapshots.... Whoa! I can take a snapshot!!!
  • Previously I was under the impression that the format couldn't be raw and had to be qcow2 - My focus was incorrectly on that. Thank you so much for the help!

--- Logical volume --- LV Path /dev/VMs/vm-101-disk-0 LV Name vm-101-disk-0 VG Name VMs LV UUID debXS0-o8Nq-8mge-lKTc-UYeR-pNC4-563lJp LV Write Access read/write LV Creation host, time pve, 2020-12-09 11:10:35 -0500 LV Pool name VMs LV Status available # open 1 LV Size 10.00 GiB Mapped size 82.26% Current LE 2560 Segments 1 Allocation inherit Read ahead sectors auto - currently set to 256 Block device 253:9 --- Volume group --- VG Name VMs System ID Format lvm2 Metadata Areas 1 Metadata Sequence No 44 VG Access read/write VG Status resizable MAX LV 0 Cur LV 3 Open LV 2 Max PV 0 Cur PV 1 Act PV 1 VG Size <119.24 GiB PE Size 4.00 MiB Total PE 30525 Alloc PE / Size 30494 / <119.12 GiB Free PE / Size 31 / 124.00 MiB VG UUID JY0caM-mMIj-DoYb-8VID-226i-eahJ-cLK5hB