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Comment by RyanKearney | Hacker News Reader

Why would anyone go with RAID 0 for a server? At least do RAID 10.

The article describes techniques for setting up RAID(0) against EC2 local ephemeral storage for performance gains. As there's no way to replace a failed drive RAID 10 wouldn't provide any benefit.

Well, you'd have complete data loss on RAID-0 if there's a single drive failure. With RAID-10, you can sustain at least one drive failure without data loss. That way, even though you can't replace a failed drive, you can at least get the data off to a new instance.

The whole instance can disappear at any time, so you can't rely on hardware redundancy. This means you must back up your data off the ephemeral drive in some fashion already, in which case going for RAID-10 doesn't provide much benefit.

Ah, I see. I'm not an EC2 customer, but how often do instances disappear? This seems kind of odd on Amazon's end. What's the reason for instances disappearing?

Hardware failure.

The four drives required for RAID 1+0 are only available on xlarge instances -- overkill for most people.

99% of the motivation for doing this is to make up for the poor performance ephemeral storage offers. Any data on these drives should be replicated to other nodes anyway, or you're doing it wrong.

You could always replace it with an EBS volume.

The whole point of the post is that he moved off of EBS for various performance and stability reasons.

keyword: ephemeral

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