[DRBD-user] Where to find review of DRBD vs Corosync

Heitor Lessa heitor.lessa at hotmail.com
Mon Aug 20 21:09:48 CEST 2012

Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.


Digimer,  Do you recommend any doc for Pacemaker studies? I started out few weeks ago but I would not like to simply copy and paste but create more sophisticated rules and create some OCF agents.
 I appreciate all help you have done.



> Date: Mon, 20 Aug 2012 09:47:24 -0400
> From: lists at alteeve.ca
> To: brucew at alcoholjustice.org
> CC: drbd-user at lists.linbit.com
> Subject: Re: [DRBD-user] Where to find review of DRBD vs Corosync
> 
> Happy to help. And ya, the cluster folks were just as helpful when I was
> starting out. It's a pretty awesome group. :)
> 
> digimer
> 
> On 08/20/2012 03:57 AM, Bruce Wolfe, M.S.W., CIO wrote:
> > TOTALLY!!! Woo-Hoo!  You're the best, Digimer. I appreciate (all of)
> > your constant patience with us newbies. This is one of the few open
> > source communities that is truly inviting and accepting to help promote
> > the use of excellent product and support.
> > 
> > Kudos to all!!
> > 
> > 
> > Bruce M. Wolfe, M.S.W., CIO
> >                  
> > 
> >          24 Belvedere St.
> >     San Rafael, CA 94901  
> > 415/456.5692  (Main Office)
> > 415/257.2493  (Direct)
> > 415/456.0491  (Fax)
> >            KI6BSL  (HAM)
> > 
> > 
> > "Most of the change we think we see in life is due to truths being in
> > and out of favor." - Robert Frost
> > ------------------------------------------------------------------------
> > 
> >     On 08/16/2012 07:38 PM, Bruce Wolfe, M.S.W., CIO wrote:
> >     > Thanks, Digimer, and greetings again.
> >     >
> >     > The configuration is:
> >     > Failover of primary to secondary.
> >     > Two nodes: one primary, one secondary in, as you say, a RAID 1
> >     > configuration.
> >     >
> >     > So, all three get used? In our current configuration, we are only
> >     using
> >     > DRBD and Heartbeat.
> > 
> >     To get automatic recovery after failure, yes, you need all three.
> > 
> >     DRBD simply replicates raw data. That's it, nothing more. Promoting a
> >     secondary node to primary requires external actions, be it by the user
> >     or via another program.
> > 
> >     Heartbeat is deprecated and has no future. Anyone using it should be
> >     making near-term plans to get off of it. So let's take the right off the
> >     table.
> > 
> >     Corosync is a stand alone tool that handles cluster membership and
> >     message passing. It doesn't care what other programs do or how they use
> >     it's message passing capabilities. It is merely a communications tool.
> >     Specifically; It decided who can send and receive messages amoungst a
> >     group of machines. In our case, we want this so that pacemaker can
> >     coordinate actions.
> > 
> >     Pacemaker is a cluster resource manager. That is, it reacts to changes
> >     in cluster membership and, based on defined policies, decides to stop,
> >     start, migrate or otherwise act on services. It doesn't care *how*
> >     machines in the cluster come and go, only that they do.
> > 
> >     So in your use case, you would setup DRBD to replicate data. Next, you
> >     would configure corosync to say "these two nodes are members of cluster
> >     X". Then you tell Pacemaker; "When both nodes are available, make node
> >     1's DRBD the primary and make node 2 secondary. However, if not 1 dies,
> >     promote node 2 to primary. When node 1 returns, demote node 2 and
> >     promote noed 1."
> > 
> >     Make sense?
> > 
> >     -- 
> >     Digimer
> >     Papers and Projects: https://alteeve.com
> > 
> > 
> 
> 
> -- 
> Digimer
> Papers and Projects: https://alteeve.ca
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