[ovirt-devel] [vdsm] VM recovery now depends on HSM

[Adam Litke]

Hi all,

As part of the new live merge feature, when vdsm starts and has to
recover existing VMs, it calls VM._syncVolumeChain to ensure that
vdsm's view of the volume chain matches libvirt's.  This involves two
kinds of operations: 1) sync VM object, 2) sync underlying storage
metadata via HSM.

This means that HSM must be up (and the storage domain(s) that the VM
is using must be accessible.  When testing some rather eccentric error
flows, I am finding this to not always be the case.

Is there a way to have VM recovery wait on HSM to come up?  How should
we respond if a required storage domain cannot be accessed?  Is there
a mechanism in vdsm to schedule an operation to be retried at a later
time?  Perhaps I could just schedule the sync and it could be retried
until the required resources are available.

Thanks for your insights.

-- 
Adam Litke