On 5/25/2010 at 07:34 AM, Dean Patterson <[email protected]> wrote: > Yes it does, thank you Ryan. So it is correct to say that I am using > corosync as the communications layer between drbd and pacemaker?
Corosync is the membership & messaging layer (how the nodes talk to each other). Pacemaker sits on top of this, and manages highly available resources (filesystem, webserver, database, whatever), i.e. Pacemaker is what will start, stop and monitor a given resource on a particular node. Pacemaker is thus responsible for starting/stopping DRBD. DRBD itself does not use corosync (it has its own means of synchronizing data between the nodes). > Then I can use an openais plugin with corosync if I need to? Yes. Installing openais on top of corosync gives you the openais plugins. You might find the following slides useful/interesting; it's fairly high level, but slide 29 has a diagram of all the bits & pieces (except you'll have to pretend the openais piece is corosync plus openais): http://ourobengr.com/high-availability-in-37-easy-steps.odp There's also audio if you've got 40 minutes to kill: http://ourobengr.com/high-availability-in-37-easy-steps.ogg http://ourobengr.com/high-availability-in-37-easy-steps.mp3 Regards, Tim > > On May 24, 2010, at 2:30 PM, Ryan O'Hara wrote: > > > On Sat, May 22, 2010 at 10:44:37PM -0700, Dean Patterson wrote: > >> Hello Digimer, > >> > >>> From what I gathered, corosync is a subset of openais meant for > >>> situations that do not require the full openais standard. They are > >>> the communications layer for pacemaker. I am using drbd so > >>> corosync is the layer between drbd and pacemaker that gives me the > >>> cluster resource management. Any corrections to this would be > >>> great as I am also still learning, but I think this is the gist of > >>> it. > > > > It depends on what version of "openais" we are talking about. Let me > > explain, and Steve can chime in with further clarification if needed. > > > > In the past (pre 1.0 release) there was just openais. It contained > > executable code, an implementation of TOTEM, a handful of SA Forum > > services. etc. During the development phase of corosync/openais 1.0, > > the old "openais" project was split into two new projects: > > > > 1. Corosync - the executables code, TOTEM implementation, CPG, etc. > > 2. OpenAIS - only SA Forum services (ie. CKPT, LCK, MSG, etc.) > > > > In its present form (1.x), openais is just a collection of libraries that > > implemented SA Forum services. These libraries can be loaded and used > > within corosync. Thus openais depends on corosync. > > > > I think the confusion comes from the fact that the "old" openais (pre > > 1.0) is all inclusive -- it contains everything. Yet when the project > > split, openais kept its name. > > > > Does this make sense? > > > > Ryan > > > > > >> On May 22, 2010, at 7:29 PM, Digimer wrote: > >> > >>> Hi all, > >>> > >>> I've been teaching myself about clustering (mainly using Red Hat's > >>> cluster suite). I've gone through most of the options in openais.conf > >>> and I think I've got a handle on it now. > >>> > >>> Where I am left wondering is the relationship of corosync and > >>> pacemaker. Neither seem to be part of RHEL/CentOS, so I've not come > >>> across anything describing what exactly they provide. > >>> > >>> Would someone mind explaining what exactly corosync and pacemaker are > >>> and how they relate to openais? Their websites seem to cover how to > >>> install them but less on what they actually do. > >>> > >>> Thanks! > >>> > >>> -- > >>> Digimer > >>> E-Mail: [email protected] > >>> AN!Whitepapers: http://alteeve.com > >>> Node Assassin: http://nodeassassin.org > >>> _______________________________________________ > >>> Openais mailing list > >>> [email protected] > >>> https://lists.linux-foundation.org/mailman/listinfo/openais > >> > >> _______________________________________________ > >> Openais mailing list > >> [email protected] > >> https://lists.linux-foundation.org/mailman/listinfo/openais > > _______________________________________________ > Openais mailing list > [email protected] > https://lists.linux-foundation.org/mailman/listinfo/openais > _______________________________________________ Openais mailing list [email protected] https://lists.linux-foundation.org/mailman/listinfo/openais
