[ceph-users] features required for live migration

Jason Dillaman jdillama at redhat.com
Tue Nov 14 06:58:15 PST 2017


Concur -- there aren't any RBD image features that should prevent live
migration when using a compatible version of librbd. If, however, you
had two hosts where librbd versions were out-of-sync and they didn't
support the same features, you could hit an issue if a VM with fancy
new features was live migrated to a host where those features aren't
supported since the destination host wouldn't be able to open the
image.

On Tue, Nov 14, 2017 at 7:55 AM, Cassiano Pilipavicius
<cassiano at tips.com.br> wrote:
> Hi Oscar, exclusive-locking should not interfere with live-migration. I have
> a small virtualization cluster backed by ceph/rbd and I can migrate all the
> VMs which RBD image have exclusive-lock enabled without any issue.
>
>
>
> Em 11/14/2017 9:47 AM, Oscar Segarra escreveu:
>
> Hi Konstantin,
>
> Thanks a lot for your advice...
>
> I'm specially interested in feature "Exclusive locking". Enabling this
> feature can affect live/offline migration? In this scenario (online/offline
> migration)  I don't know if two hosts (source and destination) need access
> to the same rbd image at the same time
>
> It looks that enabling Exlucisve locking you can enable some other
> interessant features like "Object map" and/or "Fast diff" for backups.
>
> Thanks a lot!
>
> 2017-11-14 12:26 GMT+01:00 Konstantin Shalygin <k0ste at k0ste.ru>:
>>
>> On 11/14/2017 06:19 PM, Oscar Segarra wrote:
>>
>> What I'm trying to do is reading documentation in order to understand how
>> features work and what are they for.
>>
>> http://tracker.ceph.com/issues/15000
>>
>>
>> I would also be happy to read what features have negative sides.
>>
>>
>> The problem is that documentation is not detailed enough.
>>
>> The proof-test method you suggest I think is not a good procedure because
>> I want to a void a corrpution in the future due to a bad configuration
>>
>>
>> So my recommendation: if you can wait - may be from some side you receive
>> a new information about features. Otherwise - you can set minimal features
>> (like '3') - this is enough for virtualization (snapshots, clones).
>>
>> And start your project.
>>
>> --
>> Best regards,
>> Konstantin Shalygin
>
>
>
>
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-- 
Jason


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