Sunday, October 14, 2012

Cars only have one spare tire - Be smart with redundancy

Technical folks often times are perfectionists, which means they want to build reliable, fault tolerant systems. This is a good thing, but you need to be wary of falling into the trap of overbuilding redundancy.

A wise man once reminded me that a car only has one spare tire. This came up because we were building out our disaster recovery site and the team thought it would be a good idea to have a clustered email environment, on new hardware of course, at the recovery site.

Don’t get me wrong clusters are always good, but they also cost more. Instead we decided to save the 25k that would have been used on the servers to fund a real test of our recovery plan. In hindsight it was a much better choice. A recovery site ideally is never used so why over spend on it.

We are actually debating on whether we should spend for the redundant servers we do for clusters. I mean if it’s part of a cluster already do we really need RAID drives and redundant power, or is the fact that it is already redundant good enough. The verdict is still out, and the cost to add RAID and a redundant power supply isn't that much when you only buy a few servers at a time, but for someone with a huge data center, like Google or Microsoft, the cost savings could be dramatic.

You should do the analysis on your environment and see where technology went just a little too far, and see if you can either reduce new purchases, or at least reuse some that you already made.

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