[ClusterLabs] Using "mandatory" startup order but avoiding depending clones from restart after member of parent clone fails

[Alejandro Comisario]

Delighful, thanks so much ken.

On Thu, Feb 9, 2017 at 12:49 PM, Ken Gaillot <kgaillot at redhat.com> wrote:

> On 02/09/2017 08:50 AM, Alejandro Comisario wrote:
> > Ken, thanks for yor reply.
> >
> > Since in our setup, we use active/active mysql clone, so i think that
> > order is the only way to ensure what i want.
> > So, simple question, making order "Advisory", and tiking into
> > consideration that "maybe" keystone starts before mysql, making it fail
> > because of database connecrion.
> >
> > If i set on the keystone clone (and all the dependant clones)
> > on-fail="restart" for start and monitor actions (of course setting the
> > cib option start-failure-is-fatal=false ) to make sure that if it fails,
> > it will restart till everything is ok.
> >
> > would that make sense to "workaround" that ?
> >
> > best.
>
> Yes, that would work. The default is to fail up to 1,000,000 times, then
> it will stop retrying on that node. Of course, you can clean up the
> failure to start over (or set a failure-timeout to do that automatically).
>
> > On Thu, Feb 9, 2017 at 12:18 AM, Ken Gaillot <kgaillot at redhat.com
> > <mailto:kgaillot at redhat.com>> wrote:
> >
> >     On 02/06/2017 05:25 PM, Alejandro Comisario wrote:
> >     > guys, really happy to post my first doubt.
> >     >
> >     > i'm kinda having an "conceptual" issue that's bringing me, lots of
> >     issues
> >     > i need to ensure that order of starting resources are mandatory but
> >     > that is causing me a huge issue, that is if just one of the
> members of
> >     > a clone goes down and up (but not all members) all resources
> depending
> >     > on it are restarted (wich is bad), my workaround is to set order as
> >     > advisory, but that doesnt asure strict order startup.
> >     >
> >     > eg. clone_b runs on servers_B, and depends on clone_a that runs on
> >     servers_A.
> >     >
> >     > I'll put an example on how i have everything defined between this
> >     two clones.
> >     >
> >     > ### clone_A running on servers A (location rule)
> >     > primitive p_mysql mysql-wss \
> >     > op monitor timeout=55 interval=60 enabled=true on-fail=restart \
> >     > op start timeout=475 interval=0 on-fail=restart \
> >     > op stop timeout=175 interval=0 \
> >     > params socket="/var/run/mysqld/mysqld.sock"
> >     > pid="/var/run/mysqld/mysqld.pid" test_passwd="XXX" test_user=root
> \
> >     > meta is-managed=true
> >     >
> >     > clone p_mysql-clone p_mysql \
> >     > meta target-role=Started interleave=false globally-unique=false
> >     >
> >     > location mysql_location p_mysql-clone resource-discovery=never \
> >     > rule -inf: galera ne 1
> >     >
> >     > ### clone_B running on servers B (location rule)
> >     > primitive p_keystone apache \
> >     > params configfile="/etc/apache2/apache2.conf" \
> >     > op monitor on-fail=restart interval=60s timeout=60s \
> >     > op start on-fail=restart interval=0 \
> >     > meta target-role=Started migration-threshold=2 failure-timeout=60s
> >     > resource-stickiness=300
> >     >
> >     > clone p_keystone-clone p_keystone \
> >     > meta target-role=Started interleave=false globally-unique=false
> >     >
> >     > location keystone_location p_keystone-clone
> resource-discovery=never \
> >     > rule -inf: keystone ne 1
> >     >
> >     > order p_clone-mysql-before-p_keystone INF: p_mysql-clone
> >     p_keystone-clone:start
> >     >
> >     > Again just to make my point, if p_mysql-clone looses even one
> member
> >     > of the clone, ONLY when that member gets back, all members of
> >     > p_keystone-clone gets restarted, and thats NOT what i need, so if i
> >     > change the order from mandatory to advisory, i get what i want
> >     > regarding behaviour of what happens when instances of the clone
> comes
> >     > and goes, but i loos the strictness of the startup order, which is
> >     > critial for me.
> >     >
> >     > How can i fix this problem ?
> >     > .. can i ?
> >
> >     I don't think pacemaker can model your desired situation currently.
> >
> >     In OpenStack configs that I'm familiar with, the mysql server
> (usually
> >     galera) is a master-slave clone, and the constraint used is "promote
> >     mysql then start keystone". That way, if a slave goes away and comes
> >     back, it has no effect.
>



-- 
*Alejandro Comisario*
*CTO | NUBELIU*
E-mail: alejandro at nubeliu.comCell: +54 9 11 3770 1857
_
www.nubeliu.com
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