Hi, I want to use balancer mode "upmap" for all pools. This mode is currently enable for pool "hdb_backup" with ~600TB used space. root@ld3955:~# rados df POOL_NAME          USED  OBJECTS CLONES    COPIES MISSING_ON_PRIMARY UNFOUND DEGRADED   RD_OPS      RD    WR_OPS      WR USED COMPR UNDER COMPR backup              0 B        0      0         0                  0       0        0        0     0 B         0     0 B        0 B         0 B cephfs_data     1.1 TiB    89592      0    268776                  0       0        0        0     0 B     43443 144 GiB        0 B         0 B cephfs_metadata 311 MiB       48      0       144                  0       0        0        6   6 KiB      7465 106 MiB        0 B         0 B hdb_backup      585 TiB 51077985      0 153233955                  0       0        0 12577024 4.3 TiB 281002173 523 TiB        0 B         0 B hdd             6.3 TiB   585051      0   1755153                  0       0        0  4420255  69 GiB   8219453 1.2 TiB        0 B         0 B root@ld3955:~# ceph osd lspools 11 hdb_backup 51 hdd 52 backup 57 cephfs_data 58 cephfs_metadata I started with pool "cephfs_metadata" that allocated comparable low data. At the same moment when I executed ceph config set mgr mgr/balancer/pool_ids 11,52,58 Ceph status shows increasing number of Reduced data availability: <x> pg inactive, <y> pg peering And the number of <z> slow requests are blocked > 32 sec was increasing heavily up to 180. Observing Ceph log (ceph -w) it becomes clear that there's a correlation between pg inactive and slow requests are block in my cluster. How can I start analysis why the cluster reports slow requests? THX