[openstack-dev] New migration state field and better state machine proposal.

Tang Chen tangchen at cn.fujitsu.com
Wed Oct 28 10:16:16 UTC 2015

Hi all,

Please help to review this BP:


I have post a BP to improve current migration state machine [1].
Please also refer to the picture of current migration state machine [2].

The current migration state machine has mixed 3 state machines for 
different 3 types of migration all together, which makes the whole 
migration framework unclear and hard to maintain. So a better solution 
is split it into 3 new state machines, one for each migration type.

The state of each migration object is maintained by the Migration.status 
field. After some discussion, we cannot change the current definition of 
status field because it has been exposed through API. So we'd better 
keep the current "status" field, and add an new field "state" to class 
Migration, representing the migration state in the new defined state 
machine. And also redefine the states for each type of migration.

There are also some problems in current migration type. Please refer to 
[3]. I think the migration framework refactor work relates to several 
BPs, and it is a long term work.


[1] https://blueprints.launchpad.net/nova/+spec/migration-state-machine
[2] http://paste.openstack.org/show/476954/
[3] https://blueprints.launchpad.net/nova/+spec/migration-type-refactor

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