You may have noticed that Wikipedia was down yesterday which appears to be a result of a overheating problem in their European data center.

Wikpedia's tech blog states:

“Many of our servers turned off to protect themselves. As this impacted all Wikipedia and other projects access from European users, we were forced to move all user traffic to our Florida cluster, for which we have a standard quick failover procedure in place, that changes our DNS entries.

However, shortly after we did this failover switch, it turned out that this failover mechanism was now broken, causing the DNS resolution of Wikimedia sites to stop working globally. This problem was quickly resolved, but unfortunately it may take up to an hour before access is restored for everyone, due to caching effects.

We apologize for the inconvenience this has caused.” (end of quote)

In lay terms their back-up system failed then they had to wait for DNS propagation!

Data Center Knowledge states that Wikipedia houses about 50 servers in the EvoSwitch data center in Amsterdam. EvoSwitch is a 100,000 square foot data center supported by 20 megawatts of power capacity that is generated entirely from sustainable energy sources including, solar, wind and biomass. The facility uses free cooling (fresh air economization) to reduce its use of energy for air conditioning.

It’s not clear why the cooling system for the Wikipedia servers encountered problems yesterday but that may provide a clue that new technology is still not fail-proof.

In February the Wikimedia Foundation received a $2 million grant from Google, which it will use to expand its data centers.