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