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Bartosz,

this looks like a part of our global approach to rewrite pacemaker
providers to use crm_diff command instead of cs_shadow/commit approach. (
part of
https://blueprints.launchpad.net/fuel/+spec/ha-pacemaker-improvements)

If reboot attributes do not help, then we should reconsider this approach
as a high priority one. Thank you for the update.


On Thu, May 29, 2014 at 3:06 PM, Bartosz Kupidura <bkupidura at mirantis.com>
wrote:

> Hello,
>
>
> Wiadomość napisana przez Vladimir Kuklin <vkuklin at mirantis.com> w dniu 29
> maj 2014, o godz. 12:09:
>
> > may be the problem is that you are using liftetime crm attributes
> instead of 'reboot' ones. shadow/commit is used by us because we need
> transactional behaviour in some cases. if you turn crm_shadow off, then you
> will experience problems with multi-state resources and
> location/colocation/order constraints. so we need to find a way to make
> commits transactional. there are two ways:
> > 1) rewrite corosync providers to use crm_diff command and apply it
> instead of shadow commit that can swallow cluster attributes sometimes
>
> In PoC i removed all cs_commit/cs_shadow, and looks that everything is
> working. But as you says, this can lead to problems with more complicated
> deployments.
> This need to be verified.
>
> > 2) store 'reboot' attributes instead of lifetime ones
>
> I test with —lifetime forever and reboot. No difference for
> cs_commit/cs_shadow fail.
>
> Moreover we need method to store GTID permanent (to support whole cluster
> reboot).
> If we want to stick to cs_commit/cs_shadow, we need other method to store
> GTID than crm_attribute.
>
> >
> >
> >
> > On Thu, May 29, 2014 at 12:42 PM, Bogdan Dobrelya <
> bdobrelia at mirantis.com> wrote:
> > On 05/27/14 16:44, Bartosz Kupidura wrote:
> > > Hello,
> > > Responses inline.
> > >
> > >
> > > Wiadomość napisana przez Vladimir Kuklin <vkuklin at mirantis.com> w
> dniu 27 maj 2014, o godz. 15:12:
> > >
> > >> Hi, Bartosz
> > >>
> > >> First of all, we are using openstack-dev for such discussions.
> > >>
> > >> Second, there is also Percona's RA for Percona XtraDB Cluster, which
> looks like pretty similar, although it is written in Perl. May be we could
> derive something useful from it.
> > >>
> > >> Next, if you are working on this stuff, let's make it as open for the
> community as possible. There is a blueprint for Galera OCF script:
> https://blueprints.launchpad.net/fuel/+spec/reliable-galera-ocf-script.
> It would be awesome if you wrote down the specification and sent  newer
> galera ocf code change request to fuel-library gerrit.
> > >
> > > Sure, I will update this blueprint.
> > > Change request in fuel-library:
> https://review.openstack.org/#/c/95764/
> >
> > That is a really nice catch, Bartosz, thank you. I believe we should
> > review the new OCF script thoroughly and consider omitting
> > cs_commits/cs_shadows as well. What would be the downsides?
> >
> > >
> > >>
> > >> Speaking of crm_attribute stuff. I am very surprised that you are
> saying that node attributes are altered by crm shadow commit. We are using
> similar approach in our scripts and have never faced this issue.
> > >
> > > This is probably because you update crm_attribute very rarely. And
> with my approach GTID attribute is updated every 60s on every node (3
> updates in 60s, in standard HA setup).
> > >
> > > You can try to update any attribute in loop during deploying cluster
> to trigger fail with corosync diff.
> >
> > It sounds reasonable and we should verify it.
> > I've updated the statuses for related bugs and attached them to the
> > aforementioned blueprint as well:
> > https://bugs.launchpad.net/fuel/+bug/1283062/comments/7
> > https://bugs.launchpad.net/fuel/+bug/1281592/comments/6
> >
> >
> > >
> > >>
> > >> Corosync 2.x support is in our roadmap, but we are not sure that we
> will use Corosync 2.x earlier than 6.x release series start.
> > >
> > > Yeah, moreover corosync CMAP is not synced between cluster nodes (or
> maybe im doing something wrong?). So we need other solution for this...
> > >
> >
> > We should use CMAN for Corosync 1.x, perhaps.
> >
> > >>
> > >>
> > >> On Tue, May 27, 2014 at 3:08 PM, Bartosz Kupidura <
> bkupidura at mirantis.com> wrote:
> > >> Hello guys!
> > >> I would like to start discussion on a new resource agent for
> galera/pacemaker.
> > >>
> > >> Main features:
> > >> * Support cluster boostrap
> > >> * Support reboot any node in cluster
> > >> * Support reboot whole cluster
> > >> * To determine which node have latest DB version, we should use
> galera GTID (Global Transaction ID)
> > >> * Node with latest GTID is galera PC (primary component) in case of
> reelection
> > >> * Administrator can manually set node as PC
> > >>
> > >> GTID:
> > >> * get GTID from mysqld --wsrep-recover or SQL query 'SHOW STATUS LIKE
> ‚wsrep_local_state_uuid''
> > >> * store GTID as crm_attribute for node (crm_attribute --node
> $HOSTNAME --lifetime $LIFETIME --name gtid --update $GTID)
> > >> * on every monitor/stop/start action update GTID for given node
> > >> * GTID can have 3 format:
> > >>  - XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX:123 - standard
> cluster-id:commit-id
> > >>  - XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX:-1 - standard non initialized
> cluster, 00000000-0000-0000-0000-000000000000:-1
> > >>  - XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX:INF - commit-id manually set
> to INF, force RA to create new cluster, with master on given node
> > >>
> > >> Check if reelection of PC is needed:
> > >> * (node is located in partition with quorum OR we have only 1 node
> configured in cluster) AND galera resource is not running on any node
> > >> * GTID is manually set to INF on given node
> > >>
> > >> Check if given node is PC:
> > >> * have highest GTID in cluster, in case we have more than one node
> with „highest” GTID, we use CRC32 to choose proper PC.
> > >> * GTID is manually set to INF
> > >> * in case node with highest GTID will not come back after cluster
> reboot (for example disk failure) administrator should set GTID to INF on
> other node
> > >>
> > >> I have almost ready RA: http://zynzel.spof.pl/mysql-wss
> > >>
> > >> Tested with vanila centos galera/pacemaker/corosync - OK
> > >> Tested with Fuel 4.1 - Fail
> > >>
> > >>
> > >> Fuel 4.1 with that RA will not deploy correctly, because we use
> crm_attribute to store GTID, and in manifest we use cs_shadow/cs_commit for
> every pacemaker resource.
> > >> This lead to cs_commit problem with different configuration in shadow
> copy and running configuration (running config changed by RA).
> > >> "Could not commit shadow instance [..] to the CIB: Application of an
> update diff failed”
> > >>
> > >> To solve this we can go in 2 ways:
> > >> 1) dont use cs_commit/cs_shadow in manifests
> > >> 2) store GTID in other way than crm_attribute
> > >>
> > >> IMHO 2) is better (less invasive) and we can store GTID in corosync
> CMAP (http://www.polarhome.com/service/man/generic.php?qf=corosync-cmapctl),
> but this require corosync 2.X
> > >>
> > >>
> > >> --
> > >> Mailing list: https://launchpad.net/~fuel-dev
> > >> Post to     : fuel-dev at lists.launchpad.net
> > >> Unsubscribe : https://launchpad.net/~fuel-dev
> > >> More help   : https://help.launchpad.net/ListHelp
> > >>
> > >>
> > >>
> > >> --
> > >> Yours Faithfully,
> > >> Vladimir Kuklin,
> > >> Fuel Library Tech Lead,
> > >> Mirantis, Inc.
> > >> +7 (495) 640-49-04
> > >> +7 (926) 702-39-68
> > >> Skype kuklinvv
> > >> 45bk3, Vorontsovskaya Str.
> > >> Moscow, Russia,
> > >> www.mirantis.com
> > >> www.mirantis.ru
> > >> vkuklin at mirantis.com
> > >
> > >
> >
> >
> > --
> > Best regards,
> > Bogdan Dobrelya,
> > Skype #bogdando_at_yahoo.com
> > Irc #bogdando
> >
> >
> >
> > --
> > Yours Faithfully,
> > Vladimir Kuklin,
> > Fuel Library Tech Lead,
> > Mirantis, Inc.
> > +7 (495) 640-49-04
> > +7 (926) 702-39-68
> > Skype kuklinvv
> > 45bk3, Vorontsovskaya Str.
> > Moscow, Russia,
> > www.mirantis.com
> > www.mirantis.ru
> > vkuklin at mirantis.com
>
>


-- 
Yours Faithfully,
Vladimir Kuklin,
Fuel Library Tech Lead,
Mirantis, Inc.
+7 (495) 640-49-04
+7 (926) 702-39-68
Skype kuklinvv
45bk3, Vorontsovskaya Str.
Moscow, Russia,
www.mirantis.com <http://www.mirantis.ru/>
www.mirantis.ru
vkuklin at mirantis.com
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