[Pacemaker] globally-unique clone question

[Eliot Gable]

To send in unique information, you will need to create individual instances of each. Then you will need to use location constraints to lock them down to individual nodes.

Alternatively, you could re-write the RA so that you can pass it a host-to-parameter mapping string like:

name="mydata" value="node1:www.example.com node2:www.example2.com node3:www.example3.com"

Then, inside the RA, check the hostname and use the domain that is attached to that hostname.



Eliot Gable
Senior Engineer
1228 Euclid Ave, Suite 390
Cleveland, OH 44115

Direct: 216-373-4808
Fax: 216-373-4657
egable at broadvox.net


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-----Original Message-----
From: Joe Armstrong [mailto:jarmstrong at postpath.com]
Sent: Thursday, May 21, 2009 2:53 PM
To: 'pacemaker at clusterlabs.org'
Subject: Re: [Pacemaker] globally-unique clone question



> -----Original Message-----
> From: Infos E-Blokos [mailto:infos at e-blokos.com]
> Sent: Thursday, May 21, 2009 9:16 AM
> To: pacemaker at clusterlabs.org
> Subject: Re: [Pacemaker] globally-unique clone question
>
>
> ----- Original Message -----
> From: "Eliot Gable" <egable at broadvox.net>
> To: "pacemaker at oss.clusterlabs.org" <pacemaker at clusterlabs.org>;
> "JoeArmstrong" <jarmstrong at postpath.com>
> Sent: Thursday, May 21, 2009 11:39 AM
> Subject: Re: [Pacemaker] globally-unique clone question
>
>
> > The typical usage in this case would be to make all mail servers
> serve all
> > domains (virtual domain support) and then run N instances across
> those N
> > servers. Then there is no per-server unique information to deal with.
> Then
> > you can run, for example, load sharing between the nodes using
> iptables
> > CLUSTERIP (since all nodes would then be serving the same data) and
> put a
> > constraint in the CIB that says that if the clone fails on a node,
> pull
> > that node from the load-sharing config by stopping or moving away
> your
> > load-sharing resource. At least, that's how I would do it.
> >
> >
> > Eliot Gable
> > Senior Engineer
> > 1228 Euclid Ave, Suite 390
> > Cleveland, OH 44115
> >
> > Direct: 216-373-4808
> > Fax: 216-373-4657
> > egable at broadvox.net
> >
> >
> > CONFIDENTIAL COMMUNICATION.  This e-mail and any files transmitted
> with it
> > are confidential and are intended solely for the use of the
> individual or
> > entity to whom it is addressed. If you are not the intended
> recipient,
> > please call me immediately.  BROADVOX is a registered trademark of
> > Broadvox, LLC.
> >
> > -----Original Message-----
> > From: Joe Armstrong [mailto:jarmstrong at postpath.com]
> > Sent: Thursday, May 21, 2009 11:04 AM
> > To: pacemaker at oss.clusterlabs.org
> > Subject: [Pacemaker] globally-unique clone question
> >
> > Hi All,
> >
> > I am a little confused about globally-unique clones, since there can
> be no
> > instance attributes for a clone how do you tell each clone that it is
> > unique ?
> >
> > My use case is that we need to run N instances of a mail server, each
> mail
> > server is unique in that it serves a specific domain, two mail server
> can
> > never run on the same host.  In order to provide HA we need to tell
> the
> > mail server instance what domain to serve (or what filesystem to
> mount in
> > order to get the right data/config).
> >
> > I was thinking that using globally-unique clones would be the way to
> > manage this (it makes the mutual exclusion rule easy: clone-node-
> max=1)
> > but I don't see how to make each instance unique.
> >
> > ... then again I could be mis-using the concept...
> >
> > Thanks for any pointers.
> >
> > Joe
> >
>
>
> I agree, the same for apache and postgresql with DRBD
>

Unfortunately this is not possible due to the underlying database the mail server uses - but thanks for the idea anyway.

So back to the original problem - am I mis-using the globally-unique clone concept ?

Thanks.

Joe

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