Suggestions about partitions for storing VMs QCOW2

Hello people,
I’ll receive my new laptop today after years and a lot of money saved.
Of course, I’ll use Fedora. I radicalized; no more Windows! :joy:

I’d like to have only one btrfs partition, with no swap partition.
I’ll use Zram if necessary.

I love btrfs, I made many mistakes, and with a simple reboot, it fixed all my messes.

I have another partition on my current laptop, in ext4, with all the images of VMs in QCOW2.

For my next laptop, I’d like to use my /home to store everything, so I can back up it without running Vorta as root on an external SSD as I’m doing now because of the ext4 partition.
Or it’s better to create a new partition to store the VMs images?

Then, it’s better to enable thin-provisioning or allocate the space on the disk directly?

Thanks in advance,

If the “new” partition for VMs would be on a different drive, you could gain a little bit of performance.

Other than that, I can’t see any advantage of a separate partition (unless you want a different file system like ext4 or xfs for you VMs)

If you are able store your VMs in /home, you simplify backups.

Stored in /home you only need to backup /home, independent of the file system (btrfs or ext4), and you don’t need root account or permission to backup /home (unless you somehow changed ownership of certain files to root, which should not be necessary.

Hello, and thanks for your reply.
I agree with you.

I agree, except for one thing.
The file structure where the VM files are stored is normally owned by root or qemu and is not normally user readable so back ups may not work. In fact, the default config on my system shows this

# ls -ld /var/lib/libvirt/images
drwx--x--x. 2 root root 4096 Jul 30 20:13 /var/lib/libvirt/images

# ls -l /var/lib/libvirt/images/
total 67274512
-rw-------. 1 qemu qemu  53695545344 Aug  1 09:32 fedora38.qcow2
-rw-------. 1 qemu qemu  42956488704 Jun 28 09:05 fedora-rawhide.qcow2
-rw-------. 1 root root  53695545344 Jul 30 20:43 ubuntu22.04.qcow2
-rw-------. 1 root root 137460187136 Jun  9 11:54 win11.qcow2

Thus backups likely still would require a bit of finagling to allow a user to perform the backup of those files. sudo likely would work for that purpose.

There might also be a performance penalty when storing VM images on Btrfs. But there is a known mitigation.

@iosonopiero, the type of storage you choose depends on your goals, e.g. RAW storage focuses on performance, while thin provisioinig targets the efficiency of space allocation, and a file-based storage can provide flexibility including live snapshots, live migration, etc.

Also keep in mind that hypervisor is basically a role you can run remotely, and libvirt allows connecting to remote hypervisors and manage both local and remote hosts and guests the same way, so carefully delegating this role can significantly affect the backup strategy.

@computersavvy, you are confusing system and session modes, and the latter does not require privilege elevation to access and manage the storage pool.

Thank you, people!