Can probably go anywhere, since they're separate buildings, but think about how stuff is moved around in the process.
Raw log storage > debark > sawing mill > planer > finished storage, with misc scraps and cut-off pieces from the main cutting saw going to the chipper > chip loading
Imagine also that if this is a more modern mechanised mill, the logs would be fed into the de-barker and various mechanical rollers and conveyers would continuously move the logs from the debarker to saw to planers and length cut-off saws and then the finished boards stacked and bundled at the end and moved to the storage/loading yard by forklift.
Otherwise, if the debarker is located somewhere else, then the logs need to be moved from storage to debarker, then from the debarker to the main mill.
Also consider, that a board mill might not need to de-bark, since the edges can be sliced off by the main saw. Although if they're selling their woodchips as a secondary by-product to paper mills, or actually using the chips directly to make OSB (oriented strandboard) then they might want to strip the bark first and keep the chips "clean".
But if you had a plywood or veneer mill, the logs need to be debarked before they can be put on a peeler to cut the veneer sheets.
What sort of mill do you have really?