openstack/cinder
Code Issues Proposed changes

VNX: Add constraints for async migration

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Async migration was introduced to accelerate the cloning of volume (
The cloned volume can be accessed after the migration starts, no need
to wait it for finishing).

However, before the migration finishes, snapshots cannot be created from
the source volume any more, which could affect subsequent clones from
the same source volume. That is the constraint of async migration.

The fix is adding the constraint to the doc of VNX driver. And give
users some advises on how to make the subsequent volume clone work.

Change-Id: I6ad3c6b967d5a33966b40c3a54c0f110576c8d87
Closes-bug: #1796825
This commit is contained in:
Ryan Liang 2018-10-10 17:24:34 +08:00
parent 6f1648e399
commit 3269da58d8
1 changed files with 12 additions and 0 deletions
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12
doc/source/configuration/block-storage/drivers/dell-emc-vnx-driver.rst
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@ -794,6 +794,18 @@ a volume is available for use.
To disable this feature, user can add ``--metadata async_migrate=False`` when
creating new volume from source.
**Constraints**
- Before the migration finishes, snapshots cannot be created from the source
volume, which could affect subsequent clones from the same source volume.
The typical affected use case is that creating volume-2 via cloning
volume-1 immediately after creating volume-1 via cloning volume-0. To achieve
so, users are advised to take any one of below actions:
1) wait for the first clone finishing, or
2) create volume-2 via cloning volume-0 instead of volume-1, or
3) create volume-1 with ``--metadata async_migrate=False``.
Best practice
~~~~~~~~~~~~~