I must be moving to another shard, having outgrown my current one. Its a manual operation.
Flickr tells me they’re moving my stuff around
Incidentally, I can’t sign out. Or view the main page. Or any of the groups I’m subscribed to. Its completely locked. But it does take under-15 minutes… (at least for the load I have – ~11,500 images).
Update: Read John Allspaw‘s comments at the HighScalability link to this blog post. He’s in-charge of operations, and an all round nice guy, and great presenter.