[openstack-dev] [nova] Nova Live Migration of rescued instances

Paul Carlton paul.carlton2 at hpe.com
Wed May 25 11:16:20 UTC 2016



On 25/05/16 11:59, Gary Kotton wrote:
> Hi,
> The VMware driver supports rescue. Live migration should be pretty simple here as the rescue is only for the disk. So you can migrate the instance to whatever host you want. The only concern with the VMware driver is that the live migration patches are in review and I think that they require a spec or blueprint (https://review.openstack.org/#/c/270116/)
> Thanks
> Gary
>
> On 5/25/16, 10:49 AM, "Paul Carlton" <paul.carlton2 at hpe.com> wrote:
>
>> I'm working on a spec https://review.openstack.org/#/c/307131/ to permit
>> the live migration of rescued instances. I have an implementation that
>> works for libvirt and have addressed lack of support for this feature
>> in other drivers using driver capabilities.
>>
>> I've achieved this for libvirt driver by simply changing how rescue and
>> unrescue are implemented.  In the libvirt driver rescue saves the current
>> domain xml in a local file and unrescue uses this to revert the instance to
>> its previous setup, i.e. booting from instance primary disk again rather
>> than rescue image.  However saving the previous state in the domain
>> xml file is unnecessary since during unrescue the domain is destroyed
>> and restarted. This is effectively a hard reboot so I just call hard reboot
>> during the unrescue operation.  Hard reboot rebuilds the domain xml
> >from the nova database so the domain xml file is not needed.
>> However I was wondering which other drivers support rescue, vmware
>> and xen I think?  Would it be possible to implement support for live
>> migration of rescued instances for these drivers too?  I'm happy to do
>> the work to implement this, given some guidance from those with more
>> familiarity with these drivers than I.
>>
>> Thanks
>>
>> -- 
>> Paul Carlton
>> Software Engineer
>> Cloud Services
>> Hewlett Packard
>> BUK03:T242
>> Longdown Avenue
>> Stoke Gifford
>> Bristol BS34 8QZ
>>
>> Mobile:    +44 (0)7768 994283
>> Email:    mailto:paul.carlton2 at hpe.com
>> Hewlett-Packard Limited registered Office: Cain Road, Bracknell, Berks RG12 1HN Registered No: 690597 England.
>> The contents of this message and any attachments to it are confidential and may be legally privileged. If you have received this message in error, you should delete it from your system immediately and advise the sender. To any recipient of this message within HP, unless otherwise stated you should consider this message and attachments as "HP CONFIDENTIAL".
>>
>>
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So vmware supports rescue but until this patch goes in it does not
support live migration between compute nodes?  So if my change
lands before yours then you would need to amend the
"supports_live_migrate_rescued" capabilities flag to True in your
driver to permit live migration of instances in a rescued state?

-- 
Paul Carlton
Software Engineer
Cloud Services
Hewlett Packard
BUK03:T242
Longdown Avenue
Stoke Gifford
Bristol BS34 8QZ

Mobile:    +44 (0)7768 994283
Email:    mailto:paul.carlton2 at hpe.com
Hewlett-Packard Limited registered Office: Cain Road, Bracknell, Berks RG12 1HN Registered No: 690597 England.
The contents of this message and any attachments to it are confidential and may be legally privileged. If you have received this message in error, you should delete it from your system immediately and advise the sender. To any recipient of this message within HP, unless otherwise stated you should consider this message and attachments as "HP CONFIDENTIAL".


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