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[Proxmox] High IO wait during backup on nfs causes VM freeze - Solution

Backing-up VMs on a NFS device with Proxmox can be problematic.

In my case, the backup process caused an high io-wait level that ended in a VM freeze.

The solution that i've found is to put a limit on the backup transfer bandwidth from the Proxmox machine to the NFS volume.

This is the result:


Before:

Proxmox high io wait


After:

Proxmox low io wait

How to limit backup speed on Proxmox

The software that makes backups in Proxmox is vzdump

It's configuration file is located in /etc/vzdump.conf

So edit this file with nano

nano /etc/vzdump.conf  

Remove the # from the bwlimit line and set your limit in KB/s

# vzdump default settings

#tmpdir: DIR
#dumpdir: DIR
#storage: STORAGE_ID
#mode: snapshot|suspend|stop
bwlimit: 5120  
#ionice: PRI
#lockwait: MINUTES
#stopwait: MINUTES
#size: MB
#maxfiles: N
#script: FILENAME
#exclude-path: PATHLIST

That's all

(This is my first post in English, there may be grammar errors)