Mode must be specified.
Patches are applied one zone at a time. The
patch job begins in the region with the lowest
number of targeted VMs. Within the region,
patching begins in the zone with the lowest
number of targeted VMs. If multiple regions (or
zones within a region) have the same number of
targeted VMs, a tie-breaker is achieved by
sorting the regions or zones in alphabetical
Patches are applied to VMs in all zones at
the same time.