Comment 12 for bug 1709594

Matt,
 Understood. It works well after switching to singleconductor mode.
 R.g.t. I85047d44e388c89938f80ad8be1724bd11ed0225
 Live migration without block migration requires the source and destination hosts are on the same shared storage. For xenapi driver, the implement in the above commit is to check the shared storage basing on aggregate.
 See the spec: https://specs.openstack.org/openstack/nova-specs/specs/mitaka/implemented/making_live_migration_api_friendly.html#the-detection-of-block-migration

 Instead of querying the api database, I think we can using the xenapi API to determine if the hosts are in the same host pool.