On Tue, 6 May 2008, Dennis Muhlestein wrote:
I was planning on pgpool being the cushion between the raid0 failure probability and my need for redundancy. This way, I get protection against not only disks, but cpu, memory, network cards,motherboards etc. Is this not a reasonable approach?
Since disks are by far the most likely thing to fail, I think it would be bad planning to switch to a design that doubles the chance of a disk failure taking out the server just because you're adding some server-level redundancy. Anybody who's been in this business for a while will tell you that seemingly improbable double failures happen, and if were you'd I want a plan that survived a) a single disk failure on the primary and b) a single disk failure on the secondary at the same time.
Let me strengthen that--I don't feel comfortable unless I'm able to survive a single disk failure on the primary and complete loss of the secondary (say by power supply failure), because a double failure that starts that way is a lot more likely than you might think. Especially with how awful hard drives are nowadays.
-- * Greg Smith gsmith@xxxxxxxxxxxxx http://www.gregsmith.com Baltimore, MD
