[Openstack-operators] memcached redundancy
Juan José Pavlik Salles
jjpavlik at gmail.com
Thu Aug 14 19:58:41 UTC 2014
Joe, I'm not running it in my grizzly cloud because I still have got just
one controller node. However I remember testing repcached in two VMs and it
worked ok. Anyway it may not be the best solution for a big production
cloud since repcached project is pretty dead already (last update 2012).
2014-08-14 16:38 GMT-03:00 Joe Topjian <joe at topjian.net>:
> Thanks all for the input! Aggregating all replies:
> Juan: I've seen that patch and was curious about it. When you say it
> worked for you, have you used it in OpenStack for similar reasons?
> Daneyon: ah - sticky sessions are a good idea. I will look into that.
> John: Another component is a very good possibility. I'll try this out in a
> dev environment or if we have planned maintenance where I can try this
> prior to the maintenance window. Thank you for the insight on what the
> memcached client should be doing.
> On Thu, Aug 14, 2014 at 1:22 PM, Juan José Pavlik Salles <
> jjpavlik at gmail.com> wrote:
>> It might not be the best idea ever, but it worked for me. There's a
>> memcached patch called repcached that allows you to have 2 memcached
>> servers sincronized (as far as I now, it just works for 2 servers) with
>> each other, this way you get HA and LB. The patch source is
>> https://github.com/usecide/repcached/blob/master/repcached-2.3.1-1.4.13.patch and
>> here you've got a little example
>> http://viviendolared.blogspot.com.ar/2014/01/memcached-replicado-en-ubuntu-1204-lts.html running
>> on Ubuntu 12.04 (sorry about the spanish link, but the steps are pretty
>> straight forward).
>> 2014-08-14 16:05 GMT-03:00 Daneyon Hansen (danehans) <danehans at cisco.com>
>>> It has been a while, but I believe I load-balanced memcached using
>>> HAProxy (using sticky sessions) and observed no issues with fail-over.
>>> Daneyon Hansen
>>> Software Engineer
>>> Email: danehans at cisco.com
>>> Phone: 303-718-0400
>>> From: Joe Topjian <joe at topjian.net>
>>> Date: Thursday, August 14, 2014 10:09 AM
>>> To: "openstack-operators at lists.openstack.org" <
>>> openstack-operators at lists.openstack.org>
>>> Subject: [Openstack-operators] memcached redundancy
>>> I have an OpenStack cloud with two HA cloud controllers. Each
>>> controller runs the standard controller components: glance, keystone, nova
>>> minus compute and network, cinder, horizon, mysql, rabbitmq, and memcached.
>>> Everything except memcached is accessed through haproxy and everything
>>> is working great (well, rabbit can be finicky ... I might post about that
>>> if it continues).
>>> The problem I currently have is how to effectively work with memcached
>>> in this environment. Since all components are load balanced, they need
>>> access to the same memcached servers. That's solved by the ability to
>>> specify multiple memcached servers in the various openstack config files.
>>> But if I take a server down for maintenance, I notice a 2-3 second
>>> delay in all requests. I've confirmed it's memcached by editing the list of
>>> memcached servers in the config files and the delay goes away.
>>> I'm wondering how people deploy memcached in environments like this?
>>> Are you using some type of memcached replication between servers? Or if a
>>> memcached server goes offline are you reconfiguring OpenStack to remove the
>>> offline memcached server?
>>> OpenStack-operators mailing list
>>> OpenStack-operators at lists.openstack.org
>> Pavlik Salles Juan José
>> Blog - http://viviendolared.blogspot.com
>> OpenStack-operators mailing list
>> OpenStack-operators at lists.openstack.org
> OpenStack-operators mailing list
> OpenStack-operators at lists.openstack.org
Pavlik Salles Juan José
Blog - http://viviendolared.blogspot.com
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