From d259197c24e5376ce701d3d6510ba6d78023a194 Mon Sep 17 00:00:00 2001 From: whoami-rajat Date: Mon, 1 Nov 2021 11:41:02 -0400 Subject: [PATCH] Add info about __DEFAULT__ in install docs This patch adds info regarding the __DEFAULT__ type. Also how it can be removed and who should remove it. Change-Id: I21191218720aeca22a1aefabe5171718b4d39b41 --- .../install/get-started-block-storage.rst | 40 +++++++++++++++++++ 1 file changed, 40 insertions(+) diff --git a/doc/source/install/get-started-block-storage.rst b/doc/source/install/get-started-block-storage.rst index 067b22a3c27..44c9a9c53ba 100644 --- a/doc/source/install/get-started-block-storage.rst +++ b/doc/source/install/get-started-block-storage.rst @@ -34,3 +34,43 @@ cinder-backup daemon Messaging queue Routes information between the Block Storage processes. + +The default volume type +----------------------- + +Since the Train release, it is required that each volume must have a +*volume type*, and thus the required configuration option +``default_volume_type`` must have a value. A system-defined volume type +named ``__DEFAULT__`` is created in the database during installation and +is the default value of the ``default_volume_type`` configuration option. + +You (or your deployment tool) may wish to have a different volume type that +is more suitable for your particular installation as the default type. +This can be accomplished by creating the volume type you want using the +Block Storage API, and then setting that volume type as the value for +the configuration option. (The latter operation, of course, cannot be +done via the Block Storage API.) + +The system defined ``__DEFAULT__`` volume type is a regular volume type +that may be updated or deleted. There is nothing special about it. It only +exists because there must always be at least one volume type in a cinder +deployment, and before the Block Storage API comes up, there is no way for +there to be a volume type unless the system creates it. + +Given that since the Victoria release it is possible to set a default +volume type for any project, having a volume type named ``__DEFAULT__`` +in your deployment may be confusing to your users, leading them to think this +is the type that will be assigned while creating volumes (if the user doesn't +specify one) or them specifically requesting ``__DEFAULT__`` when creating a +volume instead of the actual configured default type for the system or their +project. + +If you don't wish to use the ``__DEFAULT__`` type, you may delete it. The +Block Storage API will prevent deletion under these circumstances: + +* If ``__DEFAULT__`` is the value of the ``default_volume_type`` configuration + option then it cannot be deleted. The solution is to make a different + volume type the value of that configuration option. +* If there are volumes in the deployment of the ``__DEFAULT__`` type, then + it cannot be deleted. The solution is to retype those volumes to some + other appropriate volume type.