On Dec 1, 2007 1:30 PM, Amos Shapira <[EMAIL PROTECTED]> wrote: > > > > It is very lacking in the area of Ethernet heartbeats (allows only > one!) > > and > > > > > > What do you mean by "allows only one"? > > Exactly what it sounds like. > > That it allows only one heartbeat on the ether? Allows only one > heartbeat medium or what? > Because from what I've seen so far it's possible to have multiple > cluster's heartbeats on the same network without interruption - just > use different ports or different multicast groups or unicast, and the > documentation recommends using multiple parallel heartbeat mediums > (serial + ether, for instance) so a single medium failure won't cause > a split-brain situation (where both nodes are alive and think that > they are the master). >
Uhm. >From what I remember in RHCS4, the network heartbeat is influenced by the hostnames specified in /etc/cluster/cluster.conf, and each node tries to "ping" the other according to "getent hosts <nodeName>". This methodology allows only one IP heartbeat. (when I come to think about it "IP" is more correct then "ethernet") So you put this IP over a bonded interface, you will have HA there. I *think* (why think? because I'm not sure any more! - will explain it later on) that the multicast works only over this network interface (bonded or not) and not over any other. Anyway, when I wrote these lines it caused me to question my knowledge about RHCS, and I think that this is exactly the problem. Linux-HA is plain and simple and full of features. Veritas Cluster is simple, powerful and the most robust. But when it comes to RHCS, I always question my knowledge. Regarding serial heartbeat - this is useful when you have the two nodes in a close distance and is not helpful when you have more than two nodes in the cluster. You can also use a shared storage device for heartbeat in RHCS3 and RHCS > 4.5 (they removed the support in RHCS4.0-4.4) . But that won't help you as you don't have a shared storage. (actually, I remember reading about RHCS5 that it can use GNBD for heartbeat) > Uhm. Don't have actual experience with DRBD. Though, I find this > technology > > a bit scary. Personally I would prefer a real storage device (SAN or > NAS) > > for this kind of work (and make sure that the storage is highly > available). > > Then I can go to sleep at night ;-) > > At this point I would prefer Linux-HA (or if you really have the money: > > Veritas Cluster) > > Also my previous employer (a very large company with hundreds of > RedHat servers) used it extensively with no problem. > Can you please tell me (off-list possibly) who was this employer, and how uses DRBD? I'm really interested in such success stories from the technological aspect of it. Best regards, Noam
