Hi Thomas,
The two commands you're looking for are:
ceph osd pg-upmap-items $pg $source_osd $dest_osd
and to remove them
ceph osd rm-pg-upmap-items $pg
You need to pair this with finding which pg's are on your full osd's. I use ceph
pg dump and grep for the pool number and osd.
With respect to what Wido said about your failure domain, my testing indicated that trying
to move a pg to an osd that would violate crush rules for failure domain resulted in an
error code in the logs and no movement of the pg.
You may wish to test this yourself to be sure. I tested on 3x rep pool with host failure
domain.
Regards,
Rich