Only internal snapshots for QCOW2 disks?

[DoomedPython]

Hi all! While I'm playing around with Proxmox in my lab, namely with snapshots, I have noticed one thing: irrespective of the storage backend (NFS or directory, unless we're talking about ZFS which has snapshots), if I have QCOW2 disk on it, Proxmox will always create an internal snapshot. I have checked this with qemu-img snapshot -l against the QCOW2 disk and it lists the snapshot inside of it.

So the question is, is it indeed the only snapshot mechanism (internal snapshot) Proxmox does for QCOW2 disks? Is there any option to make it create external snapshots?

 

[intrax]

Proxmox creates btrfs snapshots on my btrfs storage, but only of qcow2 volumes.
I don't get it because seems proxmox favours zfs, which I don't want to use on my consumer ssd's !

 

[floh8]

Yes, only internal

 

[intrax]

Afaik no option for external snapshots...

 

[LnxBil]

So the question is, is it indeed the only snapshot mechanism (internal snapshot) Proxmox does for QCOW2 disks? Is there any option to make it create external snapshots?

How should that work on directory or NFS? You can create snapshots in QCOW2 (you refer to as internal) or on a storage backend that supports snapshots (you refer to as external) namely LVM-thin, ZFS, ZFS-over-iSCSI, CEPH and all other 3rd party backends that are supported, e.g. Blockridge.

 

[DoomedPython]

How should that work on directory or NFS? You can create snapshots in QCOW2 (you refer to as internal) or on a storage backend that supports snapshots (you refer to as external) namely LVM-thin, ZFS, ZFS-over-iSCSI, CEPH and all other 3rd party backends that are supported, e.g. Blockridge.

Yes, exactly. I know that the storage types/filesystems that do not have snapshot capabilities will use QCOW2 snapshots. It's just that there are two types of snapshots you can get with QCOW2: internal and external. I was wondering if it's only internal ones.

 

[DoomedPython]

Yes, only internal

Thanks!

 

[LnxBil]

QCOW2: internal and external.

What do you mean by external?

 

[dietmar]

What do you mean by external?

External qcow2 snaphots is when you create a second qcow2 file, which refers to the original as base file. New data is always written to the second file. The base file is read-only.

AFAIK ovirt is using this model.

 

[esi_y]

External qcow2 snaphots is when you create a second qcow2 file, which refers to the original as base file. New data is always written to the second file. The base file is read-only.

AFAIK ovirt is using this model.

Was this a conscious decision for PVE, i.e. to go for the internal ones? It's definitely more flexible to have separate files around.

 

[LnxBil]

External qcow2 snaphots is when you create a second qcow2 file, which refers to the original as base file. New data is always written to the second file. The base file is read-only.

AFAIK ovirt is using this model.

Ah yes ... I forgot about this. The base image stuff. Thank you for explaining.