Re: Ceph & Cinder & HA

[Loic Dachary <loic@dachary.org>]

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On 10/11/2014 11:34, Sebastien Han wrote:
> Indeed, that’s what we discussed with Giulio, using HAProxy for the Monitors is a bit overkill since the client is natively able to switch between different monitor source.
> 
> Loic, maybe you can elaborate a bit more on the usage of HAProxy for the monitors?

Hi Sebastien,

I can't elaborate because I know nothing about HAProxy (well, close to nothing ;-). I'd like to learn more about how HA (via HAProxy or something else) can leverage Ceph in a meaningfull way thouhg, hence my interest for the topic.

Cheers

> 
>> On 09 Nov 2014, at 22:54, Justin Erenkrantz <justin@erenkrantz.com> wrote:
>>
>> On Fri, Nov 7, 2014 at 4:35 AM, Giulio Fidente <gfidente@redhat.com> wrote:
>>> The architecture we're considering is as follows:
>>>
>>>  keepalived
>>>    haproxy
>>>      ceph-mon
>>>
>>> where haproxy and ceph-mon are always up on all openstack 'controller' nodes
>>> (also running cinder) and keepalived is taking care of managing a virtual ip
>>> hosted on one of those
>>
>> For Ceph, you almost certainly don't need to use keepalived or haproxy
>> as all Ceph clients will fail over to the full set of monitor IPs (you
>> need a way of distributing those IPs to the cluster -
>> chef/puppet/ansible/etc/etc can handle that).  Having
>> keepalived/haproxy in the loop for ceph-mon is one more thing that
>> could break.
>>
>> We do run cinder services behind the controller/headnodes nodes via
>> keepalived/haproxy - the "trick" such as it is for Ceph is to set all
>> the hostnames in cinder to being the same and it works okay.  See:
>>
>> https://github.com/bloomberg/chef-bcpc/blob/master/cookbooks/bcpc/templates/default/cinder.conf.erb
>>
>> We haven't seen any issues in an active/active configuration; though
>> there are some MySQL schema deadlocks that aren't necessarily related
>> to Ceph sitting in Cinder.
>>
>> Cheers.  -- justin
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> 
> 
> Cheers.
> –––– 
> Sébastien Han 
> Cloud Architect 
> 
> "Always give 100%. Unless you're giving blood."
> 
> Phone: +33 (0)1 49 70 99 72 
> Mail: sebastien.han@enovance.com 
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> Web : www.enovance.com - Twitter : @enovance 
> 

-- 
Loïc Dachary, Artisan Logiciel Libre


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