[ceph-users] Run optimizer to create a new plan on specific pool fails

Hi, I want to create an optimizer plan on each pool. My cluster has multiple crush roots, and multiple pools each representing a specific drive (HDD, SSD, NVME). Some pools are balanced, some are not. Therefore I want to run  optimizer to create a new plan on specific pool. However this fails for any pool with this error message: root@ld3955:~# ceph balancer optimize hdd-plan hdd Error EALREADY: Unable to find further optimization, or pool(s)' pg_num is decreasing, or distribution is already perfect root@ld3955:~# ceph balancer optimize ssd-plan ssd Error EALREADY: Unable to find further optimization, or pool(s)' pg_num is decreasing, or distribution is already perfect root@ld3955:~# ceph balancer optimize hdb_backup-plan hdb_backup Error EALREADY: Unable to find further optimization, or pool(s)' pg_num is decreasing, or distribution is already perfect root@ld3955:~# ceph osd pool ls hdb_backup hdd ssd nvme cephfs_data cephfs_metadata What is causing this error? THX