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

Digimer lists at alteeve.ca
Mon Aug 20 21:27:20 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.


I'm limited in what I can recommend as I am a dyed-in-the-wool Red Hat
cluster user. I do know that Andrew Beekhof's "Clusters from Scratch" is
pretty much the de-facto tutorial on pacemaker, so start there if you
haven't already.

Alternatively, ask on the pacemaker mailing list and/or on the
#linux-cluster IRC channel on freenode.net.

digimer

PS - pcmk ML -  http://oss.clusterlabs.org/mailman/listinfo/pacemaker

On 08/20/2012 03:09 PM, Heitor Lessa wrote:
> 
> 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
>> _______________________________________________
>> drbd-user mailing list
>> drbd-user at lists.linbit.com
>> http://lists.linbit.com/mailman/listinfo/drbd-user


-- 
Digimer
Papers and Projects: https://alteeve.ca



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