Strange issue on server when invoking backup

[sahostking]

When backing up a server we found that server feezes just when this is invoked and load goes from 0.8 avg to around 700+

Nov 30 12:18:01 cp-6 qemu-ga: info: guest-ping called
Nov 30 12:18:01 cp-6 qemu-ga: info: guest-fsfreeze called
Nov 30 12:18:01 cp-6 qemu-ga: info: executing fsfreeze hook with arg 'freeze'

Does this mean I should rather just not use qemu agent on linux VMs to play it safe. Its a live server with 100s of websites on.

 

[sahostking]

Yip seems I am right. Tested it first twice. Froze the VM too long and had to stop and start to get it up

Had to disable it by doing:
systemctl stop qemu-guest-agent
systemctl disable qemu-guest-agent

and reran backup and it never froze once. So all is good and stable now again. We cannot afford downtime during backups.

 

[dcsapak]

please note that the freezing/thawing of the guest fs is to have a consistent backup, if this is not done, it is possible the data in the backup is not consistent since some writes may only be in the page cache of the vm
also, instead of disabling the guest agent as a whole, you should be able to configure what the guest agent does on a freeze call (e.g. nothing), please refer to the manpage/documentation of the
specific guest-agent package inside your vm for doing this..

 

[sahostking]

I get that but having downtime is not good for a web hosting provider like us and this caused load to go from low to a extrmely high value and then vm died.

Thanks however for the advice on looking at the manpage/ documentation to change some values.