Cron – Amazon EC2 EBS volume scheduled backup/snapshots using puppet / similar tools

Your approach sounds very good - but I can think of a possible way to improve it.

To reduce the impact of data loss since the last backup, and EBS volume failure (unlikely, but still possible) you could store your data on a separate EBS volume than your system files, and back up the data volume more frequently than the system volume.

With your current strategy, you'll lose any data that was created between the time of the last backup and the time your instance failed. With the new approach, the data volume will be getting written to right up until the instance failure, so you can just reattach it to your new instance once it's up and running.

since you're striping data across the volumes, it would stand to reason that you have to put each NEW volume in the same location on the RAID as the volume from which the snapshot was created.

I tested your premise, and logical as it may seem, the observation is otherwise.

Let me detail this:
I have the exact same requirement as you do. However, the RAID0 that I am using has only 2 volumes.

I'm using Ubuntu 10 and have 2 EBS devices forming a RAID0 device formatted with XFS.

The raid0 device was creating using the following command:
sudo mdadm --create /dev/md0 --level 0 --metadata=1.1 --raid-devices 2 /dev/sdg /dev/sdh

I've installed MYSQL and a bunch of other software that are configured to use /dev/md0 to store their data files.

Using the same volumes: Once done, I umount everything, stop the Raid and reassemble it like so: sudo mdadm --assemble /dev/md0 /dev/sdh /dev/sdg The thing is that irrespective of the order of /dev/sdg /dev/sgh, the RAID reconstitutes itself correctly.

Using snapshots: Post this, I use ec2-consistent-snapshot to create snapshots of the 2 EBS disks together. I then create volumes from this disk, attach it to a new instance (that has been configured for the software already), reassemble the RAID (I've tried interchanging the order of the EBS volumes too), mount it and I'm ready to go.

Sounds strange, but it works.