Colin Charles has cool picture showing Flickr's message telling him they'll need about 15 minutes to move his 11,500 images to another shard. One, that's a lot of pictures! Two, it just goes to show you don't have to make this stuff complicated. Sure, it might be nice if their infrastructure could auto-balance shards with no down time and no loss of performance, but do you really need to go to all the extra complexity? The manual system works and though Colin would probably like his service to have been up, I am sure his day will still be a pleasant one.