Benefits of EBS vs. instance-store (and vice-versa)

Question

I'm unclear as to what benefits I get from EBS vs. instance-store for my instances on Amazon EC2. If anything, it seems that EBS is way more useful (stop, start, persist + better speed) at relatively little difference in cost...? Also, is there any metric as to whether more people are using EBS now that it's available, considering it is still relatively new?

Answer 1

The bottom line is you should almost always use EBS backed instances.

Here's why:

• EBS backed instances can be set so that they cannot be (accidentally) terminated through the API.
• EBS backed instances can be stopped when you're not using them and resumed when you need them again (like pausing a Virtual PC), at least with my usage patterns saving much more money than I spend on a few dozen GB of EBS storage.
• EBS backed instances don't lose their instance storage when they crash (not a requirement for all users, but makes recovery much faster)
• You can dynamically resize EBS instance storage.
• You can transfer the EBS instance storage to a brand new instance (useful if the hardware at Amazon you were running on gets flaky or dies, which does happen from time to time)

Adding:

• It's faster to launch an EBS backed instance because the image doesn't have to be fetched from S3.

I'm a heavy user of Amazon and switched all of my instances to EBS backed storage as soon as the technology came out of beta. I've been very happy with the result.

Answer 2

99% of our AWS setup is recyclable. So for me it doesn't really matter if I terminate an instance -- nothing is lost ever. E.g. my application is automatically deployed on an instance from SVN, our logs are written to a central syslog server.

The only benefit of instance storage that I see are cost-savings. Otherwise EBS-backed instances win. Eric mentioned all the advantages.