A number of users have reported that most of Amazon's Elastic Compute Cloud Service in North America was unavailable Wednesday evening and early Thursday.

According to a post on Amazon's forums the reason for the outage was "a lightning storm caused damage to a single Power Distribution Unit (PDU) in a single Availability Zone. While most instances were unaffected, a set of racks does not currently have power, so the instances on those racks are down. We have technicians on site, and we are working to replace the affected PDU. We do not yet have an ETA, but we expect to be able to recover the instances when we restore power. Besides these affected instances, all other instances, and all other Availability Zones, are operating normally. Users with affected instances can launch replacement instances in any of the US Region Availability Zones or wait until their instance(s) are restored"

The latest outage brings new and unneeded attention to the potential need for hybrid cloud offerings that allow for a combination of cloud services both internal and externally available. Recently Rackspace has also said that a hybrid cloud approach that combines existing data centers and cloud based resource may be the ideal deployment model for enterprises looking to use the cloud.

Needless to say, a 100% cloud based infrastructure may be problematic when the power goes out.