Importance of Redundant Power Supply

power-supply-unitredundancy

How important are redundant power supplies in servers, not measured by how critical server uptime is, but by likelihood of failure?

In other words, are server PSU's error prone and/or likely to fail within the first 3-4 years of service?

Best Answer

I had a warranty PSU exchange in maybe 30% of my devices over the years. I consider this high enough that I want redundancy for this and would recommend it wherever feasible. In fact, PSUs were the only part except HDs I ever had to replace.

There are other reasons to consider redundant power as well:

  • An UPS won't protect you from a failing PSU. This might lead to broken filesystems etc, with unnecessary high recovery times.
  • You can connect your device to two or more different breaker circuits. Depending on your environment, you might not reach your server room fast enough before the UPS runs out of juice if a breaker trips. With redundant PSUs, hopefully the second circuit will last.
  • There are devices you cannot easily keep redundant, like switches etc. Here, a second PSU is mandatory, IMHO.
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