On Oct 23, 2010, at 2:23 PM, Robinson, Eric wrote: >> Looks like you are mixing up physical connections >> and Corosync rings. > > I should not have mentioned DRBD at all as it confuses the question. > > Let me try it this way: > > How do I build a three-node Corosync cluster with redundant heartbeat > paths? I don't trust the switched network or the Ethernet bonding > drivers to be 100% reliable, and it is just good practice to have > multiple heartbeat paths. On my old 2-node clusters, I have three > heartbeat paths: the switched network, back-to-back links, and serial > cables.
At some point you would have to trust Ethernet. I think SLIP is dead :) When you have two independent switches on two different UPS you already have a redundancy, right? If you are not comfortable with just one extra path, by all means, add interfaces, add bonding, have 4 Ethernet cards in each server with 4 different switches - sky is the limit :) But I would say if you have a "backbone" switch and "drbd/iscsi/SAN" switch and still use heartbeat, it's a good enough solution for the common case. > > It sounds like you are saying that to have multiple heartbeat paths on a > 3-node Corosync cluster, each heartbeat path must be through a separate > switched network or VLAN. I can see why this would be the case. > > I was hoping that a crossover cable could be used to form a "logical" > ring between two nodes, and that I could configure two logical rings > between 3 servers. Token ring? Also dead :) > > So really, maybe I'm not trying to build a 3-node cluster. What I'm > really trying to build are two 2-node clusters where one of the physical > servers participates in BOTH 2-node clusters. CLUSTER1 would consist of > physical servers A and C. CLUSTER2 would consist of physical servers B > and C. > > So maybe what I want to know is, is it possible to run multiple > "instances" of Corosync on server C, such that it participates in two > separate clusters? You can have as many corosyncs as your memory permit, but I afraid each of them would have to run it's own DomU/VMWare/whatever :) And maybe it even can have some practical implementation, who knows > > Thanks for your patience. I had no idea this would end up being so > complicated. "3-node cluster" is much easier to say than to configure, > apparently. :-) It really isn't :) Vadym _______________________________________________ Linux-HA mailing list [email protected] http://lists.linux-ha.org/mailman/listinfo/linux-ha See also: http://linux-ha.org/ReportingProblems
