Hello everyone, After discussing a few failure scenarios with different people on OFTC network #ceph, I wanted to make sure that the following makes sense. I have 2 Data Centers, please see attachment and I want to make sure that if Data Center 1 (DC1) fails data recovery should be possible on Data Center 2 (DC2) As you can see on the diagram, I have 8 OSD's in total, 4 on each DC. Using an Erasure Coded pool I've set the crush-failure-domain=rack. - 2 DC's - 8 OSD's in total - EC pool profile used crush-device-class= crush-failure-domain=rack crush-root=default jerasure-per-chunk-alignment=false k=2 m=2 plugin=jerasure technique=reed_sol_van w=8 Current crush layout: # ceph osd df tree ID CLASS WEIGHT REWEIGHT SIZE USE AVAIL %USE VAR PGS TYPE NAME -1 1.56238 - 1.6 TiB 280 GiB 1.3 TiB 17.47 1.00 - root default -22 0.39059 - 400 GiB 70 GiB 330 GiB 17.48 1.00 - rack rack1-dc1 -3 0.19530 - 200 GiB 35 GiB 165 GiB 17.45 1.00 - host th-dev-ceph-osd-tc01 7 hdd 0.19530 1.00000 200 GiB 35 GiB 165 GiB 17.45 1.00 195 osd.7 -5 0.19530 - 200 GiB 35 GiB 165 GiB 17.50 1.00 - host th-dev-ceph-osd-tc02 1 hdd 0.19530 0.98708 200 GiB 35 GiB 165 GiB 17.50 1.00 195 osd.1 -20 0.39059 - 400 GiB 70 GiB 330 GiB 17.47 1.00 - rack rack1-dc2 -13 0.19530 - 200 GiB 35 GiB 165 GiB 17.49 1.00 - host th-dev-ceph-osd-wp01 5 hdd 0.19530 1.00000 200 GiB 35 GiB 165 GiB 17.49 1.00 198 osd.5 -11 0.19530 - 200 GiB 35 GiB 165 GiB 17.45 1.00 - host th-dev-ceph-osd-wp02 0 hdd 0.19530 1.00000 200 GiB 35 GiB 165 GiB 17.45 1.00 197 osd.0 -19 0.39059 - 400 GiB 70 GiB 330 GiB 17.46 1.00 - rack rack2-dc1 -7 0.19530 - 200 GiB 35 GiB 165 GiB 17.35 0.99 - host th-dev-ceph-osd-tc03 2 hdd 0.19530 1.00000 200 GiB 35 GiB 165 GiB 17.35 0.99 198 osd.2 -15 0.19530 - 200 GiB 35 GiB 165 GiB 17.57 1.01 - host th-dev-ceph-osd-tc04 6 hdd 0.19530 1.00000 200 GiB 35 GiB 165 GiB 17.57 1.01 198 osd.6 -21 0.39059 - 400 GiB 70 GiB 330 GiB 17.48 1.00 - rack rack2-dc2 -9 0.19530 - 200 GiB 35 GiB 165 GiB 17.46 1.00 - host th-dev-ceph-osd-wp03 3 hdd 0.19530 1.00000 200 GiB 35 GiB 165 GiB 17.46 1.00 197 osd.3 -17 0.19530 - 200 GiB 35 GiB 165 GiB 17.50 1.00 - host th-dev-ceph-osd-wp04 4 hdd 0.19530 1.00000 200 GiB 35 GiB 165 GiB 17.50 1.00 198 osd.4 TOTAL 1.6 TiB 280 GiB 1.3 TiB 17.47 MIN/MAX VAR: 0.99/1.01 STDDEV: 0.06 I am aware that this is not optimal so please advise. What EC profile should I chose, what should k and m values be and should I use LRC instead of JERASURE algorithm considering the attached jpeg. Thank you very much in advance! -- Met vriendelijke groeten, Kind regards, Valentin Bajrami Target Holding
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