User gets to decide priority and threshold-factor for each of the limits.

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option scheduler adaptive-lu
# Order and threshols of selected schedulers
option threshold disk-usage(2048000) file-usage(32) mem-usage(4096) disk-speed(4096)
# 6th node is a slow storage
option brick-priority 1-5:0, 6:100
# Include only the bricks that has at-least 60GB free disk space
option disk-minimum-free 61440000000
--------------------------------------------------

Explaination:
=============
if (> (- max-du min-du) 2GB), pick the min-du
if (> (- max-file-usage min-file-usage) 32) pick min-file-usage
..
if (> (- fastest-disk-speed slowest-disk-speed) 4MBps) pick fastest-disk-speed

Apply priority, when more than one brick is selected by above logic.
Apply rand(count) if more than one brick has same priority.

--
Anand Babu

Adaptive Least (resource) Used xlator for distributing file creating on subvolumes