[openstack-dev] glance db upgrades question
Brian Lamar
brian.lamar at rackspace.com
Mon Mar 11 22:23:33 UTC 2013
+1 -- Can't wait to talk about this more. This is a big blocker across all projects from a CI/CD standpoint.
On Mar 11, 2013, at 5:25 PM, Mark Washenberger <mark.washenberger at markwash.net> wrote:
> Hi Tom,
>
> Unfortunately, Glance does not support rolling db upgrades. Actually,
> I'm not aware of any OpenStack project that supports such upgrades. So
> far, I believe that deployments that require very high uptime are
> advised to carefully manage and even at times rewrite the database
> migrations.
>
> I'm not happy with this situation, and supporting rolling upgrades in
> Glance is on my personal roadmap. However, there are number of
> difficult issues we need to tackle to make that work. First we'll need
> to refactor the code away from the use of declarative sqlalchemy
> models, towards an approach that allows the domain models and database
> schemas to be versioned independently. Second, we'll need to come up
> with a testing procedure that can enforce the practices that make
> rolling upgrades possible. Last (that I know of) we'll need to figure
> out a way to communicate the relative significance of each commit to
> deployers, as each can have potentially different strategies for the
> best way to distribute the change out into their cluster. If we do
> eventually provide support for rolling upgrades, its going to be a
> daunting task, made much harder by the variety of possible OpenStack
> deployments that need to be considered.
>
> This is a subject I'm very excited about. If there are others with
> ideas for how we might make progress towards rolling upgrades, I'm
> very happy to brainstorm about ways to incorporate these ideas into
> Glance. I anticipate adding support will be easier in Glance, due to
> the relative simplicity of the project and its data model.
>
> Thanks,
> markwash
>
> On Mon, Mar 11, 2013 at 4:55 AM, Hancock, Tom (HP Cloud Services)
> <Tom.Hancock at hp.com> wrote:
>> I’m happy to be corrected on this as I’m basing it on reading a diff, not an
>> actual test.
>>
>> It looks like glance migration 19 could introduce a non backwards compatible
>> change
>>
>> to the glance database. In principle, how should such an upgrade be managed?
>>
>>
>>
>> A ‘rolling’ upgrade would be an ideal way to minimize disruptive updates.
>>
>> It looks like there would need to be a bounce upgrade (stop the service on
>> all nodes;
>>
>> upgrade sw; start service) as old and new db clients don’t look like they
>> will co-exist.
>>
>>
>>
>> thanks,
>>
>> Tom
>>
>>
>>
>> ---
>>
>> Tomas Hancock, HP Cloud Services, Hewlett Packard, Galway. Ireland
>> +353-91-754765
>>
>> Postal Address : Hewlett Packard Galway Limited, European Software Centre,
>> Ballybrit Business Park, Galway, Ireland
>> Registered Office: Hewlett Packard Galway Limited, 63-74 Sir John Rogerson's
>> Quay, Dublin 2 Registered Number: 361933
>>
>> 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".
>>
>>
>>
>>
>> _______________________________________________
>> OpenStack-dev mailing list
>> OpenStack-dev at lists.openstack.org
>> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
>>
>
> _______________________________________________
> OpenStack-dev mailing list
> OpenStack-dev at lists.openstack.org
> http://lists.openstack.org/cgi-bin/mailman/listinfo/openstack-dev
More information about the OpenStack-dev
mailing list