On Mon, Jun 15, 2009 at 11:43 AM, Marcin Krol<[email protected]> wrote: > Serge Dubrouski wrote: >> This one is much better: >> http://www.clusterlabs.org/mediawiki/images/f/fb/Configuration_Explained.pdf > > Thanks! That's greatly appreciated. > >>>>> - resource supporting active-active configuration; do you mean like >>>>> Apache instances in 2 resource groups configured to use different IP >>>>> addresses so they would not conflict? >>>> I mean that Apache should have a shared filesystem underneath it or >>>> some kind of another mechanism that will make sure that both instances >>>> have the same content. Also if you try to make an active-active >>>> filesystem you have to make sure that it support concurrent access on >>>> different nodes, i.e. you have to use something like OCFS2 or so. >>> Hmm I was thinking rather of 2 different iSCSI targets or NDB devices, 1 >>> for each resource group -- is switching them possible on failover / >>> failback? >> >> Then it's not active/active is it? > > I'm sorry? Perhaps I imagine it in a wrong way, but suppose node 1 has > resource group, say, apache_a on iSCSI target A, and node 2 has resource > group apache_b on iSCSI target B. > > Now, both are running their res. groups simultaneously (hence I think of > them as active/active), and on the node 1 failing, node 2 mounts iSCSI > target B and starts rg apache_b. And vice versa. > > Is that not active/active?
No. It's 2 different resources working in active/passive configuration each. Active/Active means something like Oracle RAC when several cluster nodes provide access to the same database at the same time. With Pacemaker a.k.a CRM you can run different resources on different cluster nodes without any problems. You can even have the same resource up on several nodes using clones but as I said your resource has to be able to support it. > > More importantly, is such configuration achievable using > Heartbeat/Pacemaker and CRM (cause that's the holy grail I'm trying to > build)? > >> OCFS2 can be used for shared filesystem and as far as I know Oracle >> recommends it for using even in Oracle RAC, MySQL is a different thing >> though. I don't know how to build an active/active MySQL cluster and >> I'm pretty sure that it requires more that a shared FS, the database >> itself should support concurrent access from different nodes to its >> data. > > Thanks! > > Regards, > mk > > _______________________________________________ > Linux-HA mailing list > [email protected] > http://lists.linux-ha.org/mailman/listinfo/linux-ha > See also: http://linux-ha.org/ReportingProblems > -- Serge Dubrouski. _______________________________________________ Linux-HA mailing list [email protected] http://lists.linux-ha.org/mailman/listinfo/linux-ha See also: http://linux-ha.org/ReportingProblems
