[openstack-dev] [nova] BUG? nova-compute should delete unused instance files on boot

Joshua Harlow harlowja at yahoo-inc.com
Mon Oct 7 22:49:29 UTC 2013


This brings up another question, do people actually like/use the
'local_delete' feature in nova?

In general it seems to free resources that are not actually capable of
being freed and has been problematic for y! usage.

Deleting from the DB allows another request to actually take those
resources over, yet the previous VM (+network,volumes...) that wasn't
deleted still has those resources (likely attached to it in the case of a
volume, or in the case of a hypervisor the VM resource is still active,
but maybe nova-compute is down) so u end up in a conflict. How are others
using this code? Has it been working out?

-Josh

On 10/7/13 3:34 PM, "Vishvananda Ishaya" <vishvananda at gmail.com> wrote:

>There is a configuration option stating what to do with instances that
>are still in the hypervisor but have been deleted from the database. I
>think you want:
>
>running_deleted_instance_action=reap
>
>You probably also want
>
>resume_guests_state_on_host_boot=true
>
>to bring back the instances that were running before the node was powered
>off. We should definitely consider changing the default of these two
>values since I think the default values are probably not what most people
>would want.
>
>Vish
>On Oct 7, 2013, at 1:24 PM, Chris Friesen <chris.friesen at windriver.com>
>wrote:
>
>> On 10/07/2013 12:44 PM, Russell Bryant wrote:
>>> On 10/07/2013 02:28 PM, Chris Friesen wrote:
>>>> 
>>>> I've been doing a lot of instance creation/deletion/evacuate and I've
>>>> noticed that if I
>>>> 
>>>> 1)create an instance
>>>> 2) power off the compute node it was running on
>>>> 3) delete the instance
>>>> 4) boot up the compute node
>>>> 
>>>> then the instance rootfs stays around in /var/lib/nova/instances/.
>>>> Eventually this could add up to significant amounts of space.
>>>> 
>>>> 
>>>> Is this expected behaviour?  (This is on grizzly, so maybe havana is
>>>> different.)  If not, should I file a bug for it?
>>>> 
>>>> I think it would make sense for the compute node to come up, query all
>>>> the instances in /var/lib/nova/instances/, and delete the ones for
>>>> instances that aren't in the database.
>>> 
>>> How long are you waiting after starting up the compute node?  I would
>>> expect it to get cleaned up by a periodic task, so you might have to
>>> wait roughly 10 minutes (by default).
>> 
>> This is nearly 50 minutes after booting up the compute node:
>> 
>> cfriesen at compute2:/var/lib/nova/instances$ ls -1
>> 39e459b1-3878-41db-aaaf-7c7d0dfa2b19
>> 41a60975-d6b8-468e-90bc-d7de58c2124d
>> 46aec2ae-b6de-4503-a238-af736f81f1a4
>> 50ec3d89-1c9d-4c28-adaf-26c924dfa3ed
>> _base
>> c6ec71a3-658c-4c7c-aa42-cc26296ce7fb
>> c72845e9-0d34-459f-b602-bb2ee409728b
>> compute_nodes
>> locks
>> 
>> Of these, only two show up in "nova list".
>> 
>> Chris
>> 
>> 
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>
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