Between September 26 and September 30, Amazon Web Services is planning to reboot many of its EC2 cloud computing instances. The company said it is applying software patches that require a reboot, and that some instances "will be unavailable for a few minutes." Because the company is staggering the reboot of different regions, it expects that many of its large customers will not experience any downtime. However, it added, "We understand that for a small subset of customers the reboot will be more inconvenient; we wouldn’t inconvenience our customers if it wasn’t important and time-critical to apply this update."
Amazon isn't providing a lot of details about the reason for the reboot, but industry insiders believe it is related to flaw in the Xen hypervisor. Amazon did say that the reboot was not related to the Shell Shock vulnerability in Linux and Unix that was reported yesterday.