Last night Rackspace Cloud had some downtime. Reading post-mortems is always instructive, so let’s see what we can learn from Rackspace.

It sounds like this downtime was caused by a power issue:

We were testing phase rotation on a Power Distribution Unit (PDU) when a short occurred and caused us to lose the PDUs behind this Cluster. The phase rotation allows us to verify synchronization of power between primary and secondary sources.