Several public cloud computing vendors, including Amazon, Rackspace, Linode and IBM have notified customers of impending reboots due to a security issue with the Xen hypervisor. The vulnerability in question will be disclosed March 10, prompting the cloud vendors to update their systems before them.
Not all customers will be affected. Amazon has said that the issue impacts less than 10 percent of EC2 instances.
This isn't the first time the Xen hypervisor has resulted in downtime for cloud customers; a similar issue prompted reboots last September.