One of the problems with clouds is that they have this tendency to rain as it did on Amazon’s Simple Storage Service (S3) on Sunday when it was down – and not for the first time – in both the US and Europe for something like eight hours – translating into less than 2Nines availability in a month (not a year, a month).

Users couldn’t access their stored data – a particularly scary situation for a cloud-dependent business.

The problem extended to Amazon’s Elastic Compute Cloud (EC2) and prevented new virtual machines from being set up.

Amazon said it was an issue with the “communication between several Amazon S3 internal components,” which doesn’t exactly explain what happened now does it?

Amazon, which had to take the system offline to fix the problem, said no data was lost and that customers will be automatically credited for the downtime.

An outage in February was reportedly caused by too many authentication requests.

Google’s Documents and Spreadsheets service went down for about 45 minutes a couple of weeks ago.

By the way, Amazon’s quarterly profit doubled to $158 million on sales up 41% to $4.06 billion.