Backup thin provisioned VM to NFS

[johnoatwork]

Hi All, I've been toying with Proxmox for a few years but this is my first post to this forum. So greetings.

I have a question in relation to backing up a thin provisioned disk to an NFS share, more specifically a VM in a local ZFS pool to an ext4 NFS share.

Will the disk be expanded to its full size when written to the NFS share? That is, if the disk size is 30GB but only 3GB is used by ZFS, will it be 30GB or 3GB on the NFS share?

This is a design issue I'm currently struggling with and I would appreciate any insight.

Thanks

 

[oguz]

hi,

no the disk will not be expanded into full size on the NFS share (it will also be compressed).

 

[johnoatwork]

hi,

no the disk will not be expanded into full size on the NFS share (it will also be compressed).

Thanks oguz. The last post in this thread suggests that NFS above 4.1 will allow trim, at least for VMs running on the share. I might give it a try but my own experience moving thin provisioned disks around is that they get expanded. I'm pretty sure I could use zfs over iscsi but believe I would need another server because as far as I know Proxmox can't be set up as an iscsi target.

I'll post the outcome here for posterity and thanks again.

 

[oguz]

the thread you linked is talking about having the VM disk stored on the nfs share so that's a different case.

in this case when you're making a backup of a VM from a thinprovisioned storage to NFS, the size of the backup archive won't be close the disk itself (unless it's considerably full)