NFS Performance / Cifs 3.1

[Nachtfalke]

Sparse is the default on px 3.1, the vm's disks are preallocated but only take up as much space as they actually use. Which worked on my nas - 512gb hd only occupied 20gb but the backup seemed to process the entire 512gb. Converting to thin provisioned changed backups from 3 hours to 20 minutes.

Sent from my MT27i using Tapatalk

Ah ok. I now understand what you mean but how do I do that with my qcow2 VMs? Or do I have to change from qcow2 to raw? Changing to raw is not what I want. I have in mind that some things do not work with raw which do with qcow2 (snapshots, backups, live backups or something like that).

I appreciate your help!

 

[blackpaw]

Hi Nachtfalke, just be aware I am relatively new to proxmox so I could be talking out of my ass I detailed in a thread my testing with backups and nfs:

http://forum.proxmox.com/threads/17205-Appalling-Backup-Performance

However I my problem was backing up from nfs to a USB drive (mounted as a local directory). You're backing up from a (?) SR to a nfs or cifs share. But if your source SR is nfs you might be running into the same problem.

Testing is simple enough, if a bit time consuming. You keep the drive as qcow2

1. Stop your VM
2. login to the proxmox box
3. Change to the dir where the VM's disk is
   1. cd /mnt/pve/<SR NAME>/images/<VM ID>
4. disk will be a file, probably:
   vm-<VM ID>-disk-1.qcow2
5. Verify file the size of the HD
   1. "ls -lh" to get the allocated size
   2. "du -h vm-<VM ID>-disk-1.qcow2" to get the actual size
6. ren the hard disk image
   1. "mv vm-<VM ID>-disk-1.qcow2 vm-<VM ID>-disk-1.qcow2.sparse"
7. Convert to thin provisioned (the original will be untouched)
   1. "qemu-img convert -p -f qcow2 -O qcow2 vm-<VM ID>-disk-1.qcow2.sparse vm-<VM ID>-disk-1.qcow2"
8. a "ls -lh" should now show its actual size rather than allocated.
9. check it runs ok
10. Do a backup

The conversion process is not linear, so the percentage progress will be slow at first, then speed up. Took me about an hour to convert a 40GB, 512GB allocated HD.

Cheers.

 

[Nachtfalke]

Hi,

the source of the VM is my local proxmox server with builtin HDD. I am backing up to a NAS which can only talk cifs...

Thanky for the qemu-img command. This is what I didn't know. Unfortunately I do not have enough disk space on my HDD to store the "old" and the "new" qcow2 image. So I will have to check where to get some place to do that. And unfortunately again I do not have a second linux machine where I could do the conversion or something like that. lol. This is so crazy