We have a ceph cluster with a cephfs filesystem that we use mostly for backups. When I do a "ceph -s" or a "ceph df", it reports lots of space: data: pools: 3 pools, 4104 pgs objects: 1.09 G objects, 944 TiB usage: 1.5 PiB used, 1.0 PiB / 2.5 PiB avail GLOBAL: SIZE AVAIL RAW USED %RAW USED 2.5 PiB 1.0 PiB 1.5 PiB 59.76 POOLS: NAME ID USED %USED MAX AVAIL OBJECTS cephfs_data 2 944 TiB 87.63 133 TiB 880988429 cephfs_metadata 3 128 MiB 0 62 TiB 206535313 .rgw.root 4 0 B 0 62 TiB 0 The whole thing consists of 2 pools: metadata (regular default replication) and data (erasure k:5 m:2). The global raw space reports 2.5 PiB total, with 1.0 PiB still available. But, when the ceph filesystem is mounted, it only reports 1.1 PB total, and the filesystem is almost full: Filesystem Size Used Avail Use% Mounted on x.x.x.x:yyyy:/ 1.1P 944T 134T 88% /backups So, where is the rest of my space? Or what am I missing? Thanks!