[ovirt-users] Re: split brain scenario?
On Sat, Jan 23, 2021 at 5:18 PM Henry lol <pub.virtualization(a)gmail.com> wrote:
Hi,
according to HA VM documentation, a paused VM may be started on another host and later
resumed on the original host.
- https://www.ovirt.org/develop/ha-vms.html
here, I'm assuming the HA VM was paused due to I/O error.
but I'm wondering how it can happen because I guess the HA VM will be restarted on
another host only after it's completely killed from the original host.
This is true for normal VMs, but not for HA VMs. These can be started
on another host even if we don't know if the VM is still running on the
original host. An example use case is host becoming disconnected from
the management network, or host having a hardware issue.
can you give the split brain scenario?
HA VM is using a storage lease, so it cannot have a split brain.
When VM is paused, it releases the lease. When VM is resumed,
it tries to acquire the lease before resuming, and resume will fail
if the lease is owned by another host.
If you start the HA VM on another host, the other host will acquire
the storage lease. Resuming the original paused VM will fail.
Nir