Also, migration will often get ahead of client data arriving so the
migration process will start and stop a bunch when doing it this way.  Not
unusual at all.  As Adam pointed out, there are two numbers: utilization and
% migratable.  %migratable is probably staying at or near 0 for you, while
utilization is going up.  That number will almost always be 100% if
cache=yes for the pool.

Why not let the backups run to the diskpool with highmig set to 90% and then
migrate later?  That's what most folks do.

Kelly J. Lipp
Storage Solutions Specialists, Inc.
PO Box 51313
Colorado Springs CO 80949
719-531-5926
www.storsol.com
lipp AT storsol DOT com