Background:
Given 3PAR backend configured with replication setup, currently only
Active/Passive replication is supported by 3PAR in OpenStack. When
failover happens, nova does not support volume force-detach (from
dead primary backend) / re-attach to secondary backend. Storage
engineer's manual intervention is required.
Proposed Solution:
Given a system with Peer Persistence configured and replicated volume
is created. When this volume is attached to an instance, vlun would be
created automatically in secondary backend, in addition to primary
backend. So that when a failover happens, it is seamless.
This solution would apply under following conditions:
1] multipath is enabled
2] replication mode is set as "sync"
3] quorum witness is configured
Closes bug: #1839140
Change-Id: I2d0342adace69314bd159d3d6415a87ff29db562
46a16f1d61