in Mirrorview/A if migrating to the same-size LUN, the primary or secondary LUN may be migrated at any time.                But if migrating to a larger-size LUN , then follow the below steps  If the Lun is a Secondary Image, remove it from the Mirrored relationship.  If the LUN is the Primary Image, remove all secondary images from the mirrored relationship and destroy the mirror.  and also make sure source and destination luns are not expanding .
I inherited a system that had several meta luns.  Someone used the expand feature insted of just migrating smaller LUNs to larger ones.  The meta LUNs were cancatinated and whoever created them must have used block size to specify the size of the LUN.  In this case the LUN was 36.001gb.  I really want to move this to a traditional pool LUN.  I created a traditional LUN of the same size in blocks.  I then migrated the meta LUN to the traditional LUN.  Now I'm trying to create a new LUN of 72gb and move the 36.001gb traditional pool LUN to it, but when I try to migrate to the 72gb LUN it tells me there are no availible LUNs to migrate to.  It will allow me to choose a lun of the same size similar to the rules for a meta LUN.  Have the properties of the meta LUN followed the migration to the traditional LUN?  The LUN is mirrored but I factured it before I stated.
LUN migration question