Talk:High-availability cluster

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[edit] Difference between Mirroring, Failover, Clustering and Load balancing?

What is the difference between Disk mirroring, Failover, High-availability clusters (a.k.a. Clustering?) and Load balancing?

I would like to see a concise comparison of concepts across all of these pages, as all of these concepts seems tightly bound, and perhaps some of them are identical.

--Eptin 22:00, 9 September 2007 (UTC)

They are all different but overlapping to some degree; a clear explanation would help. Let me review all the articles and see where to begin. Georgewilliamherbert 20:40, 10 September 2007 (UTC)

I added a Node reliability section to the article here on HA clustering, which should address some of your questions. To explain a bit here in summary:

• Disk mirroring is a technology to help keep computers from failing. It's usually used in HA clusters, to make the individual computer nodes used as reliable as possible. It's often used by non-clustered systems, for the same reason.
• Failover is the term for the process when a service is moved to another system, either due to a crash or due to manual intervention. HA clusters use failover as the way to get around system or application crashes.
• Load balancing clusters are a different type of cluster, where the application can be run with many copies at the same time (like webservers) safely, and some type of system in front of it parcels out the work to be done. HA clusters are for when only one copy of the application can be running - if the one computer running the application fails, then it's moved elsewhere. Load balancing has several copies running at once. Any of them can serve a request, and if one crashes others will keep going.

I hope this is helpful. Georgewilliamherbert 21:09, 11 September 2007 (UTC)