From 3269da58d8fb6cdbb902487914e7a6dedee8b22f Mon Sep 17 00:00:00 2001 From: Ryan Liang Date: Wed, 10 Oct 2018 17:24:34 +0800 Subject: [PATCH] VNX: Add constraints for async migration 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 --- .../block-storage/drivers/dell-emc-vnx-driver.rst | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/doc/source/configuration/block-storage/drivers/dell-emc-vnx-driver.rst b/doc/source/configuration/block-storage/drivers/dell-emc-vnx-driver.rst index 6606df819c6..bba1b117ab0 100644 --- a/doc/source/configuration/block-storage/drivers/dell-emc-vnx-driver.rst +++ b/doc/source/configuration/block-storage/drivers/dell-emc-vnx-driver.rst @@ -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 ~~~~~~~~~~~~~