There should be and option in "remove-brick" command (or some similar command) to migrate the data in a brick to other bricks before removing that brick. This would be *extremely* useful in dealing with a distributed/replicated filesystem with a computer and/or brick that is dead or likely to be down for an extended period (I configure bricks to be replicated between different computers). The remove-brick command on startup could make an estimate whether the data would fit on the remaining bricks. If after the migration started it turned out that the data really does not all fit there would still would not be any loss as long as the last file movement wasn't completely committed.  The command then could be aborted.