[Openstack-operators] [openstack-dev] [masakari][nova] Allow evacuation of instances in resized state

Chris Friesen chris.friesen at windriver.com
Wed Jul 19 16:35:47 UTC 2017

On 07/12/2017 06:57 PM, Jay Pipes wrote:
> On 07/04/2017 05:21 AM, Kekane, Abhishek wrote:
>> Hi operators,
>> I want to know how evacuation of resized instances is handled in real
>> environment.
>> For example if the vm is in resized state and if the compute host on which the
>> vm is resized goes down, then how will operator evacuate the vm.
>> One possible way is to reset that vm state to error and then evacuate it to
>> new compute host.
>> Please refer below scenario for reference:
>> Scenario:
>> =========
>> Pre-conditions:
>> --------------------
>> 1. Config option allow_resize_to_same_host is False.
>> 2. Instance path is not mounted on shared storage.
>> 3. Three compute nodes: "compute node A", "compute node B" and "compute node C"
>> Steps:
>> --------
>> 1. Boot an instance on "compute node A".
>> 2. User tries to resize the newly created instance and nova-scheduler selects
>> "compute node B" as a destination node for resize.
>>     In this case nova creates a instance directory on destination "compute
>> node B" and mark the instance directory which is present on the source
>> "compute node A" as "*_resize".
>> Note that the resize operation is yet not confirmed and "compute node B" goes
>> down.
>> 3. Reset instance state to ERROR as nova allows evacuation only if instance
>> state is 'ACTIVE', 'STOPPED' or 'ERROR'.
> I don't understand why you would do this, Abhishek. Why not REVERT the resize
> operation (which would clean up the _resize directory and files on the original
> host A) and then try the resize again?

Sorry for the delayed reply (just got back from vacation).  If the dest compute 
node is dead, is it even possible to revert the resize?


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