Open Stack

Hello,

I'm trying to live migrate some VMs from CentOS 7 to Rocky 8.
Everything run smoothly when there is no extra specs on flavors but 
things getting more complicated when those are fixed. Especially when 
using quota:vif_burst for QOS.
I know that we aren't supposed to use this for QOS now but it's an old 
cluster and it was done that way at the time. So VMs kinda have all 
those specs tied to them.

When live migrate a VM this show up in the nova's logs :
driver.py _live_migration_operation nova.virt.libvirt.driver  Live 
Migration failure: internal error: Child process (tc class add dev 
tapxxxxxxxx-xx parent 1: classid 1:1 htb rate 250000kbps ceil 
2000000kbps burst 60000000kb quantum 21333) unexpected exit status 1: 
Illegal "burst"
This bug cover the problem : https://bugs.launchpad.net/nova/+bug/1960840
So it's seems to be a normal behavior. Plus I forgot to mention that I'm 
on OpenStack Train version and the file mentioned in the launchpad is 
not present for this version.
By using Rocky 8 I have to use an updated libvirt that won't accept the 
burst parameter we used to set. All available versions of libvirt on 
Rocky 8 have changed behavior concerning the burst parameter.

I've done some testing to make things works including removing the 
extra_specs on flavors and in the DB, removing it through libvirt and 
trying to modify tc rules used by a VM but it didn't worked.
I have not tried yet to patch Nova or Libvirt but I don't really know 
where to look for.
The only thing that did work was to resize the VM to an identical flavor 
without the extra_specs. But this induce a complete reboot of the VM. I 
would like, if possible, to be able to live migrate the VMs which is 
quite easier.

Is it possible to remove the extra_specs on the VMs and then live 
migrate ? Or should I just plan to resize/reboot all VMs without those 
extra_specs ?
Any advise will be appreciated.

Thank you for any help,
Best regards.

Jahson
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