No QCOW2 on ZFS?

[drdownload]

If I store an VM Image on an ZFS storage I only get RAW as option for image format.

I assume it's because ZFS supports thin provisioning.

 

[tschanness]

If you want QCOW2 you need to add the storage as "Folder".

Regards, Jonas

 

[wolfgang]

No,
with zfs pool plugin you use zvols what is the bock device emulation.
So you have a raw device in qemu.

 

[wolfgang]

If you want QCOW2 you need to add the storage as "Folder".

Never do this because qcow is cow and zfs also.
A cow fs on a cow fs will kill the performance and bring no benefit or features.

 

[Nemesiz]

Maybe someone use qcow2 on zfs because of personal reasons like temporary or migration between different storage formats.

 

[tom]

Maybe someone use qcow2 on zfs because of personal reasons like temporary or migration between different storage formats.

As long as you ZFS as a directory storage, then you can store any file, also qcow2 files. But this is NOT recommended, see above.

 

[LnxBil]

bring no benefit or features.

Oh yes it does have benefits! Yes, plural!
* you can jump in between snapshots without cloning
* create snapshot trees
Both is unavailable in ZFS, so using cow2 on a zfs-based directory (if you only have ZFS available) is the only way to achieve this.

I use it quite often and never experienced any bottlenecks, yet I know that COW-on-COW has its drawbacks, but the benefits outweigh the drawbacks in my case.

 

[drdownload]

I never thought about drawbacks of cow on cow to be honest. Thanks for the clearification!.

Since I only use proxmox with my homelab (at work we use VMware) I maybe switch to ext4 for my proxmox drives.

 

[fireon]

maybe switch to ext4 for my proxmox drives.

Yes, do that Storage is depending on features that you need for. For Migrations, copy and testing qcow2 on ext4 is the easiest way.

But for all other things in productive environments with no HW-Raid ZFS or Ceph are real the best
With HW-Raid use LVM-Thin.

 

[fcymk2]

Never do this because qcow is cow and zfs also.
A cow fs on a cow fs will kill the performance and bring no benefit or features.

If use directory and raw format? Are there any disadvantages to this?

Sometimes need to copy the disk to another machine.

 

[wolfgang]

Are there any disadvantages to this?

you have no snapshots.
but ZFS as dir with raw is technical ok.

Sometimes need to copy the disk to another machine.

I would use backup/restore.

 

[LnxBil]

Sometimes need to copy the disk to another machine.

With ZFS ZVOL you will have a raw disk, you just have to read it and transfer it:

dd if=/dev/rpool/proxmox/vm-100-disk-1 bs=128k | ssh 1.2.3.4 dd bs=128K of=my-disk.raw

 

[fcymk2]

With ZFS ZVOL you will have a raw disk, you just have to read it and transfer it:

dd if=/dev/rpool/proxmox/vm-100-disk-1 bs=128k | ssh 1.2.3.4 dd bs=128K of=my-disk.raw

thanks very much