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Hi, regarding the proposed Cinder volume replication patch, < https://review.openstack.org/#/c/64026  >:

The replication driver methods are create_replica(), swap_replica(), delete_replica(),
replication_status_check(), enable_replica(), and disable_replica().

What are the expected semantics of the enable and disable methods?  In 
enable_vol_replication() it looks like the intent is that replicas are created by
create, than started by enable (and vice versa for disable/delete).

Are the plugin's enable/disable method intended for just a one-time start and
stop of the replication or are they expected to be able to cleanly pause and
resume the replication process? Is disable expected to flush volume contents
all the way through to the replica?


Another question is what is the expected usage of "primary_replication_unit_id"
and "secondary_replication_unit_id" in the "replication_relationships" table.
Are these optional? Are they the type of fields that could go in the "driver_data"
field for the relationship?


Thanks,

 -bruce