Also worth noting is that Amazon isn't forcing you to use EBS. They also have tons of fast local storage available to RAID as you wish.
Even for people who didn't use EC2 the existence of the platform caused more people to rethink their architectures to try to rely less on Important Nodes.
EBS is a step back from that philosophy and it's a point worth noting.
One of the great things this post does is enumerates some of the underlying reasons why relying on EBS will inevitably lead to more failures and in ways that are harder and harder to diagnose.
Amazon doesn't use EBS itself, right? Isn't EBS something that AWS allowed its customers to nag it into against (what it considers) its better judgement?
Only our master and our slave backup server runs on EBS. We aren't as write oriented so we can live with some of the limitations of EBS, but we've even considered moving our master MySQL and Mongo servers to ephemeral storage and just relying on our slave back database server to run on EBS (for which we take freeze/snapshots of often). That server rarely ever falls more behind in relay updates.
They are typically available as /dev/sd[bcde]
In centOS, implementing a RAID-0 block device across 2 ephemeral disks that is present on an m1.large instance can be done via the following:
mdadm --create /dev/md0 --metadata=1.1 --level=0 --quiet --run -c 256 -n 2 /dev/sdb /dev/sdc
You'll then need to format the block device with your fs of choice. Then mount it from there.
ephemeral
WHEN your EC2 node disappears (and it will), you will lose everything on that RAID.
That's not a bad thing if you know it'll happen and plan for it, but do be aware of it.