Friday, January 22, 2010

Best Solution For HA and Network Load Balancing?

SkyHi @ Friday, January 22, 2010
supaneko writes "I am working with a non-profit that will eventually host a massive online self-help archive and community (using FTP and HTTP services). We are expecting 1,000+ unique visitors / day. I know that having only one server to serve this number of people is not a great idea, so I began to look into clusters. After a bit of reading I determined that I am looking for high availability, in case of hardware fault, and network load balancing, which will allow the load to be shared among the two to six servers that we hope to purchase. What I have not been able to determine is the 'perfect' solution that would offer efficiency, ease-of-use, simple maintenance, enjoyable performance, and a notably better experience when compared to other setups. Reading about Windows 2003 Clustering makes the whole process sounds easy, while Linux and FreeBSD just seem overly complicated. But is this truly the case? What have you all done for clustering solutions that worked out well? What key features should I be aware for successful cluster setup (hubs, wiring, hardware, software, same servers across the board, etc.)?"

You'll need something that detects the primary server is offline and switches to the backup automatically. You might also want to have a separate database server that mirrors the primary DB if you're storing a lot of user content, plus a backup for it (though the backup DB server could always be the same physical machine as one of the backup webservers).

On this note, if you're comfortable (and your application is compatible) with Linux+Apache, then heartbeat [] and DRBD [] will do this and are relatively simple to get up and running. Just avoid trying to use the heartbeat v2-style config (for simplicity), make sure both the database and apache are controlled by heartbeat, and don't forget to put your DB on the DRBD-replicated disk (vastly simpler than trying to deal with DB-level replication, and more than adequate for such a low load).

Oh, and don't forget to keep regular backups of your DB somewhere else other than those two machines.