[Zak]

I recently had an EBS volume lose data for no apparent reason. I'm not a heavy EC2 user at all - I was just doing some memory/cpu-heavy stuff that wouldn't fit in to RAM on my laptop and using EBS as a temporary store so I could transfer data using a cheap micro instance and only spin up the big expensive instances when everything was in place. I ended up downloading files on an m2.4xlarge because the files I had just downloaded to the EBS volume vanished.

[saurik]

Are you certain the data left the filesystem buffer and actually got acknowledged by EBS?

[Zak]

No; I'm very much a beginner when it comes to EC2. I unmounted the filesystem, detached the volume, then shut down the instance.