[ClusterLabs] staggered resource start/stop

[Klaus Wenninger]

On 3/31/21 11:11 AM, d tbsky wrote:
> Klaus Wenninger <kwenning at redhat.com>
>> In this case it might be useful not to wait some defined time
>> hoping startup of the VM would have gone far enough that
>> the IO load has already decayed enough.
>> What about a resource that checks for something running
>> inside the VM that indicates that startup has completed?
>> Don't remember if the VirtualDomain RA might already
>> have such a probe possibility.
>     in my experience, windows will eat most of disk IO, but linux
> suffers. rhel7/rhel8 sometimes timeout mount /boot or / when disk IO
> is too heavy, but windows always boot successfully.
> resource check inside the VM is good, but I wonder if detecting failed
> for some reason the cluster will stuck. in my case I think boot by
> order and  delay can solve 99% of problem. it just looks a little
> complex with many delay RA.
>
Guess that heavily depends on what you are running inside your VMs.
If the services inside don't need each other or anything provided by
the other cluster-resources (or other way round) or everything is
synchronizing independently from the cluster ...
What you could still do is make the timeout more generous and combine
it with checking for a certain boot-state - so that it either proceeds
after the generous timeout (when something is broken inside the VM)
or if a certain state is reached.

Klaus