Note: "permalinks" may not be as permanent as we would like,
direct links of old sources may well be a few messages off.
From: "Robinson, Eric" <eric.robinson at psmnv.com> > We have the opportunity to establish a DR site in another data > center over a high bandwidth connection (2-4Gbps). One thing that > concerns me is the greater possibility of split-brain scenarios. > Currently our clusters communicate heartbeat through multiple paths. > If we move the standby cluster nodes to the secondary facility, > there will no longer be redundancy on the heartbeat links. > Everything will go through the inter-data-center connection. Should > I be very concerned? We've had a very similar setup (2 datacenters separated by ~20 miles, no redundant heartbeat links) for several years. The only time it caused any problems is when one of the main switches in the secondary datacenter failed. When the switch *came back up*, every DRBD cluster split-brained and required manual intervention to get back to a reasonable state. Switch failures are pretty rare, though. > Is there a way to minimize the risk of split-brain over WAN? If it's switch failure you're looking to guard against, put a quorum server that's in a third datacenter into your cluster management config. That *should* fix that particular problem, since the machine that can't see the quorum server or its peer should release all its resources. It makes things more complicated, though, since you need yet another machine that's in yet another place. Make sure you test the whole thing out before you get a set of frantic text messages at 0-dark-thirty, just in case. -- Matt G / Dances With Crows The Crow202 Blog: http://crow202.org/wordpress/ There is no Darkness in Eternity/But only Light too dim for us to see