On Fri, 2008-11-21 at 03:54 +0200, Brain Stormer wrote: > Hello, > > Could any component from the `Red Hat Cluster Suite` be utilized to > achieve a geographical load-balancing and high-availability system ? > > I know how to do load-balancing/high-availability when both nodes are > allocated in the same network however it happens that I have 2 nodes > allocated in different places with different IP pool so I think > calling it geographical is the proper word. > > Also if the `Red Hat Cluster Suite` does not have anything related to > that, its might be helpful to know other techniques to achieve such > goal. > > Any input is appreciated! I think the only thing that RHCS can't provide is an LVS director with layer 3 routing capabilities. You need this in order to migrate the IP addresses the services are published on between your two geographical locations. Once you can do this, your directors can encapsulate packets from the client back to your real servers using the ip-ip kernel module. My institution runs directors with keepalived and quagga OSPF routers on them. The rest can be done with standard RHCS, the only other non-standard thing you'll have to think about involves the multicasting of cluster communications. The main gotcha with this is that you have to set up an iptables rule to mangle the routing TTL of the multicast cluster communications packets to a large enough number of hops (the default is 1, which means it won't get outside your LAN) to get from one site to the other via the longest reasonable route. e.g. iptables -A OUTPUT -d <destination_multicast_addr> -j TTL --ttl-set 30 Think about the security of multicast routing these communications as well. The new CLVM RAID 1 coming in RHEL5.3 probably means that you can do all this without expensive proprietary back-end storage mirroring too. A couple of other points: * it really helps if you have good control of all the infrastructure between the two sites * the risk of split-brain is certainly higher than having all cluster nodes in the one datacentre. Regards, Nik -- Linux-cluster mailing list Linux-cluster@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/linux-cluster
