Comment 13 for bug 1039471

Yes, retrieval would require some extra work, something like

if (object.storageClass == glacier) {
  alert("Restoring data from Glacier. This will take 3 to 5 hours. Told ya!")
  while (object.restore != complete) wait()
object = downloadFromS3(object)

Obviously, restoring one object at a time will make it horribly slow, but I think as long as you keep talking to S3 only, it shouldn't be much more work than that.

The more important question though is how moving files to Glacier would have an impact on performing backups. If any. If it didn't, it would be safe to user these rules already - with the need to restore files manually from Glacier to S3 before they can be restored from S3.