I just attached another ebs volume to running instance. But how do I access the volume? I can't find the /dev/sda directory anywhere. Where should I look?
Amazon EBS snapshots capture changed blocks from a baseline, so snapshots will often be much smaller than the source volume. Billing is based on the actual size, which is nice. However, I cannot find a way to determine the snapshot actual size. ec2-describe-snaphots only provides the size of the volume that was snapshotted.
If for no other reason, I need this information to verify billing. But I'd also like to have it because I may find that by reconfiguring my volumes, and what I do with them, I can reduce the size of my incremental snapshots.
I have been poking around Amazon EC2, and am a little confused on some of the terminology. Specifically with regard to AMI, snapshots and volumes, and an EBS
Please correct me if I am wrong, or fill in any serious gaps in my following statements:
An AMI (Amazon Machine Image) is a full 'disk' capture of an operating system and configuration. When you launch an instance, you launch it from an AMI
An EBS (Elastic Block Storage) is a way to persist the state of any modifications you made once booting from a given AMI. In my mind, this is sort of like a diff on the final state of your instance vs the AMI.
A snapshot is ... well, I'm not sure. I can only assume it is a snapshot of a specific instance, but it is not clear to me how this differs from the state stored in an EBS. How is a snapshot different from creating an EBS AMI from an existing instance?
A volume is ... it would seem mounted disk space into which an AMI/EBS pair is loaded? I'm not sure on this one either. I can see (from the AWS Console) that you can create a volume from a snapshot, and that you can attach/detach volumes, but it isn't clear to me why or when you would do that.
I have seen this answer for growing EBS volumes, but I would like to shrink one.
The default Ubuntu Server images are 15 GB while I really need only 2 GB max (I use a different volume for data). Is there a way to shrink the size of the volume?
According to the Amazon EC2 FAQ, when an instance is terminated the data is gone. What steps can I take to preserve data in the event my instance is rebooted? I've been looking into EBS and S3 - would either of these be useful to store an active database? How often are instances rebooted anyways?