[Openstack] VM disk affinity during live migration

Lau Jay jay.lau.513 at gmail.com
Sat Jun 1 04:39:40 UTC 2013


Hi Chris,

I think that you are using live migration without specifying target host,
right? OpenStack cannot handle your case for now, but it has very flexible
framework to enable you DIY your migration logic.

1) Make sure SSD or SAS can be reported by nova compute, you might want to
update nova compute driver to report those metrics?
2) Add a new scheduler filter to do your logic checking for SSD and SAS.

Thanks,

Jay



2013/6/1 Chris Bartels <chris at christopherbartels.com>

> Thanks for your reply.****
>
> ** **
>
> Your reply implies that its possible to ensure that the disks stay on the
> right target manually. What would you have to do to make sure this happened?
> ****
>
> ** **
>
> The SAS space is 228GB & the SSD space is only 64GB.****
>
> ** **
>
> So the SAS disk image wouldn’t fit on the SSD, but the SSD image would fit
> on the SAS, so the migration system I imagine wouldn’t be able to screw it
> up since it would have to keep the large SAS image on the SAS target, and
> would then only be able to place the smaller SSD image on the SSD.****
>
> ** **
>
> But you say it’s a work in progress so that could mean anything could
> happen.****
>
> ** **
>
> What does the actual process look like when I would migrate a VM from one
> server to another? What exactly would I have to do to make sure it went
> right?****
>
> ** **
>
> Thanks.****
>
> ** **
>
> *From:* Alex Glikson [mailto:GLIKSON at il.ibm.com]
> *Sent:* Friday, May 31, 2013 7:34 AM
> *To:* chris at christopherbartels.com
> *Cc:* openstack at lists.launchpad.net
> *Subject:* Re: [Openstack] VM disk affinity during live migration****
>
> ** **
>
> There is an ongoing work to refactor live migration code, including use of
> scheduler to find/validate placement. At the moment the admin would need to
> make sure he/she is doing the right thing.
>
> Regards,
> Alex
>
>
>
> ====================================================================================================
> Alex Glikson
> Manager, Cloud Operating System Technologies, IBM Haifa Research Lab
> http://w3.haifa.ibm.com/dept/stt/cloud_sys.html |
> http://www.research.ibm.com/haifa/dept/stt/cloud_sys.shtml
> Email: glikson at il.ibm.com | Phone: +972-4-8281085 | Mobile:
> +972-54-6466667 | Fax: +972-4-8296112
>
>
>
>
> From:        "Chris Bartels" <chris at christopherbartels.com>
> To:        <openstack at lists.launchpad.net>,
> Date:        31/05/2013 02:12 PM
> Subject:        [Openstack] VM disk affinity during live migration
> Sent by:        "Openstack" <
> openstack-bounces+glikson=il.ibm.com at lists.launchpad.net> ****
> ------------------------------
>
>
>
>
> Hi,
>
> Please forgive me if I’ve asked already here on the list- I didn’t get a
> reply & I really need an answer, so I’m asking again in simpler terms this
> time.
>
> If I have a cluster of servers, each with spindle drives & SSDs, how can I
> be sure VM disks which reside on spindle drives migrate to spindle drives &
> those which reside on SSDs stay on SSDs as they migrate between servers?
>
> Thanks,
> Chris_______________________________________________
> Mailing list: https://launchpad.net/~openstack
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