Jerry,

We are at MVS 2.1.10 and have seen this problem. This problem started
appearing about 1 month ago.  Our config is similiar to yours.  Our
backup storage pool is apx. 10GB, Min is 70 Max is 90 during the nightly
backups.

We have not figured out why this is happening.  It seems as though the %
Migr is not correct.  I turned cache off to the STG pool and have not
had the same problem since.  I did notice however that the %Migr and
%Util do not always match (you'd think they should when cache is turned
off).  Once all backup sessions completed these numbers would match up.
--
"Things which matter most must never be at the
"Things which matter most must never be at the
mercy of things which matter least." - Goethe