PowerOn of a partition in paused state not working

[Andreas Scheuring]

- do an inband shutdown of an instance (e.g. via linux shell: shutdown -P now)
- partition state switches "Paused"
- try to start that partition again.

-> Probably nothing will happen (just tested it with zhmcclient but not yet with nova-dpm)
The issue is, that dpm is not able to "start" a partition in "paused" state.

the workaround is to "stop" the partition and then "start" it.

I also opened an issues against zhmcclient [1] - not sure which is the best place to fix it.

[1] https://github.com/zhmcclient/python-zhmcclient/issues/228

[Andreas Scheuring (andreas-scheuring)]

Had a chat with Andy. This will not be handled in the zhmcclient but we should handle that in nova-dpm! Therefore Andy will improve the error handling of the zhmcclient (see issue)

[OpenStack Infra (hudson-openstack)]

Fix proposed to branch: master
Review: https://review.openstack.org/478812

[Prabhat Ranjan (pranjank)]

This bug seems invalid.

I tried in kvm.
1. I paused instance
2. Then tried to start, shutdown, soft reboot. Nothing is working. The Error message was "NOT ALLOWED TO START/SHUTDOWN/REBOOT"
3. Then only operation after PAUSE is 'RESUME'(from horizon dashboard).
4. But the actual operation after PAUSE is UNPAUSE. https://docs.openstack.org/user-guide/cli-stop-and-start-an-instance.html

[Andreas Scheuring (andreas-scheuring)]

I guess you're mixing up things!

It's NOT about the paused state in openstack. It's about the paused state of a partition on the HMC. A partition gets into paused state if you do an inband shutdown. Just login to a dpm partition and do a shutdown -P now - then the partition is in paused state. I don't know what the state will be in openstack then - maybe we'll face another bug there.... Ideally it goes to "shutdown" or "poweoff" in openstack. Then you should be able to start it again using openstack power on. However that won't work cause poweron does a partition.start which is not an valid operation if the partition is in paused state.

[Prabhat Ranjan (pranjank)]

This issue is resolved with this patch
https://review.openstack.org/#/c/478812/

But the problem is
the sync operation happens after 10 minutes
https://github.com/openstack/nova/blob/master/nova/conf/compute.py#L681

Means When we do inband shutdown 'shutdown -P now' then openstack is aware after 10 minutes.
till 10 minutes it will be in 'Running' state. After that automatically it will be in shutdown.

Is this solution is fine or shall we decrease sync time?

[Andreas Scheuring (andreas-scheuring)]

I think that's fine. This is not worse than on other hypervisors and the user can teak it with the config option you mentioned.

[OpenStack Infra (hudson-openstack)]

Reviewed: https://review.openstack.org/478812
Committed: https://git.openstack.org/cgit/openstack/nova-dpm/commit/?id=fb4abd53d35a6be76a02962221d8cb8e24960b5e
Submitter: Jenkins
Branch: master

commit fb4abd53d35a6be76a02962221d8cb8e24960b5e
Author: Prabhat Ranjan <email address hidden>
Date: Thu Jun 29 14:37:05 2017 +0530

    PowerOn of a partition in paused state not working

    When we do inband shutdown of partition using
    command 'shutdown -P now'
    Then partition is not going to 'stopped' state.
    It is going to 'PAUSED' state.

    In DPM there is no such implementation so that we
    can start partition from PAUSED state. So workaround
    is we need to stop the partition then start.

    This patch also includes the cases when partition is
    in "starting/stopping" state.

    Closes-Bug: #1678002

    Change-Id: I1898b85a8441c3175db0a6de6d620bca19af69ec
    Signed-off-by: Prabhat Ranjan <email address hidden>