Amazon EC2 now allows you to create crash-consistent AMIs from instances with multiple EBS volumes without rebooting instances

You will now be able to create crash-consistent Amazon Machine Images (AMIs) of your Amazon EBS-backed multi-volume instance without requiring a reboot. The AMI created will retain data from all completed I/O operations of each volume attached to the instance. This ensures that you can launch an instance from the AMI and return to the exact state prior to creation of the image.