kvm / qemu / libvirt vm smart startup delay / boot order control in virt-manager / xml config

Latest response

I'd love a simple gui spot to enter the startup delay for each vm. But why stop there, the system has soo much great information that we could use to make a "smart" startup delay. I'd like a startup delay that allows me to choose a time or parameters that need to be met to startup the vm. For example. The most important to me would be load. Delay startup for 10 minutes or load less than 5.

I know this is a trivial thing to put in place, just pick your startup script and write:

sleep 60

virsh start sv100


To add the load check just a simple bash loop.

The delay would add another feature in hyperv (I assume in the rest) and the smart delay would be better than hyperv :).




Perhaps a boot order would be of some use? The virtio balloon takes time to load in the windows kernel this could be handled simply by a boot order.

Hey Brian, I apologize that we haven't seen much traction on your post yet. Did you make any progress since the 21st? Otherwise I'll track down some assistance.


Henry Hutton
Community Manager

Nope, I did find out this is a more important issue than i thought due to the KSM module (memory deduplication).

If all the machines start at once there is a much more significant risk that the memory pressure on boot will force the system into swap due to all the physical ram being used and no dedup having taken place yet. A staged startup would reduce the likely hood of RAM exhaustion.




One thing you can do is uncomment START_DELAY=0 in the /etc/sysconfig/libvirt-guests file and change the 0 to some number of seconds. That causes the libvirt-guests service to wait the number of seconds you set between each guest startup.