Hi Our 17.2.7 cluster: " -33 886.00842 datacenter 714 -7 209.93135 host ceph-hdd1 -69 69.86389 host ceph-flash1 -6 188.09579 host ceph-hdd2 -3 233.57649 host ceph-hdd3 -12 184.54091 host ceph-hdd4 -34 824.47168 datacenter DCN -73 69.86389 host ceph-flash2 -5 252.27127 host ceph-hdd14 -2 201.78067 host ceph-hdd5 -81 288.26501 host ceph-hdd6 -31 264.56207 host ceph-hdd7 -36 1284.48621 datacenter TBA -77 69.86389 host ceph-flash3 -21 190.83224 host ceph-hdd8 -29 199.08838 host ceph-hdd9 -11 193.85382 host ceph-hdd10 -9 237.28154 host ceph-hdd11 -26 187.19536 host ceph-hdd12 -4 206.37102 host ceph-hdd13 " We recently created an EC 4+5 pool with failure domain datacenter. The DCN datacenter only had 2 hdd hosts so we added one more to make it possible at all, since each DC needs 3 shards, as I understand it. Backfill was really slow though, so we just added another host to the DCN datacenter. Backfill looks like this: " data: volumes: 1/1 healthy pools: 13 pools, 11153 pgs objects: 311.53M objects, 1000 TiB usage: 1.6 PiB used, 1.6 PiB / 3.2 PiB avail pgs: 60/1669775060 objects degraded (0.000%) 373356926/1669775060 objects misplaced (22.360%) 5944 active+clean 5177 active+remapped+backfill_wait 22 active+remapped+backfilling 4 active+recovery_wait+degraded+remapped 3 active+recovery_wait+remapped 2 active+recovery_wait+degraded 1 active+recovering+degraded+remapped io: client: 73 MiB/s rd, 339 MiB/s wr, 1.06k op/s rd, 561 op/s wr recovery: 1.2 GiB/s, 313 objects/s " Given that the first host added had 19 OSDs, with none of them anywhere near the target capacity, and the one we just added has 22 empty OSDs, having just 22 PGs backfilling and 1 recovering seems somewhat underwhelming. Is this to be expected with such a pool? Mclock profile is high_recovery_ops. Mvh. Torkil -- Torkil Svensgaard Sysadmin MR-Forskningssektionen, afs. 714 DRCMR, Danish Research Centre for Magnetic Resonance Hvidovre Hospital Kettegård Allé 30 DK-2650 Hvidovre Denmark Tel: +45 386 22828 E-mail: torkil@drcmr.dk