I am looking at backup options within AWS and while instance snapshots are the obvious way to go I am have some concerns about using that method.

I'd like to take daily snapshots of each instance without stopping the instance (as they are production instances) however if I do this I am concerned that a file may be in the process of changing in some way or haven't been written to disk as yet. I am concerned that the files stored in the snapshot would possibly be corrupt due to this.

Of all my instances are EBS backed and are running linux, are my concerns valid and should I be looking at another way to back up in AWS?

Thanks!

  • 1
    Snapshot isn't really meant to be a backup solution. – Lance Robbins Sep 18 at 16:10
  • Snapshots are a good way to restore a server if it fails. They're not a good way to be able to restore individual files. – Tim Sep 18 at 19:25

Your concern is valid, snapshots may lose or corrupt some files.

To minimise the risk it is better if you ensure the disk cache is flushed using the old sync command just before taking the snapshot. Also if your architecture supports it because it is replicate you can stop any replicated in another instance service, sync and then take the snapshot. It still has risk and snapshots aren't meant to be used as a reliable source of backup but may be valid for some use cases, when there's not much access to the disk.

Snapshots in EBS behave much like LVM snapshots but considering that the snapshoted disk is connected thru network. Of course, a snapshotting stopped servers almost eliminates the risk of file corruption.

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