We run a bunch of Ubuntu instances on Amazon EC2 and over the last two months we've observed a few of them becoming unresponsive and unreachable. No SSH, no ping responses, etc. Eventually rebooting those instances helped as a last resort.
All of the affected instances are EBS-based. There are no indications as to the reason of failure in the logs. We've been suspecting that maybe the instances could somehow drop the connection to their EBS volumes.
My questions are:
- Is this even possible (I mean: an instance losing the connection to its EBS volume)?
- How do I go about debugging this and ensuring this is the case?
- Most importantly: how do I prevent this?