Hi Ceph squid. We currently have all our ceph servers at one physical location but in different rooms. We are looking at creating a new pool with some servers placed at a different physical location. Current crush map is this: root default datacenter 714 hosts datacenter HX1 hosts datacenter UX1 hosts Sample rule: { "rule_id": 0, "rule_name": "rbd_ec_data", "type": 3, "steps": [ { "op": "set_chooseleaf_tries", "num": 5 }, { "op": "set_choose_tries", "num": 100 }, { "op": "take", "item": -24, "item_name": "default~hdd" }, { "op": "choose_indep", "num": 0, "type": "datacenter" }, { "op": "chooseleaf_indep", "num": 2, "type": "host" }, { "op": "emit" } ] }, New crush map: root default datacenter HVH room 714 hosts room HX1 hosts room UX1 hosts datacenter TBA hosts Edited rule, changed root from default to HVH and failure domain from datacenter to room: { "rule_id": 0, "rule_name": "rbd_ec_data", "type": 3, "steps": [ { "op": "set_chooseleaf_tries", "num": 5 }, { "op": "set_choose_tries", "num": 100 }, { "op": "take", "item": -24, "item_name": "HVH~hdd" }, { "op": "choose_indep", "num": 0, "type": "room" }, { "op": "chooseleaf_indep", "num": 2, "type": "host" }, { "op": "emit" } ] }, Does that look right? Can we just set norebalance, move hosts around in the crush map, edit our crush rules, run pgremapper and unset norebalance? 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