Hi Christian, On 11/11/2014 13:09, Christian Balzer wrote: > On Tue, 11 Nov 2014 17:14:49 +0530 Mallikarjun Biradar wrote: > >> Hi all >> >> When Issued ceph osd dump it displays weight for that osd as 1 and when >> issued osd tree it displays 0.35 >> > > There are many threads about this, google is your friend. For example: > https://www.mail-archive.com/ceph-users@xxxxxxxxxxxxxx/msg11010.html > > In short, one is the CRUSH weight (usually based on the capacity of the > OSD), the other is the OSD weight (or reweight in the tree display). > > For example think about a cluster with 100 2TB OSDs and you're planning to > replace them (bit by bit) with 4TB OSDs. But the hard disks are the same > speed, so if you would just replace things, more and more data would > migrate to your bigger OSDs, making the whole cluster actually slower. > Setting the OSD weight (reweight) to 0.5 for the 4TB OSDs (untiil the > replacement is complete) will result in them getting the same allocation as > the 2TB ones, keeping things even. It is a great example. Would you like to add it to http://ceph.com/docs/giant/rados/operations/control/#osd-subsystem ? If you do not have time, I volunteer to do it :-) Cheers > > Christian > >> output from osd dump: >> { "osd": 20, >> "uuid": "b2a97a29-1b8a-43e4-a4b0-fd9ee351086e", >> "up": 1, >> "in": 1, >> "weight": "1.000000", >> "primary_affinity": "1.000000", >> "last_clean_begin": 0, >> "last_clean_end": 0, >> "up_from": 103, >> "up_thru": 106, >> "down_at": 0, >> "lost_at": 0, >> "public_addr": "10.242.43.116:6820\/27623", >> "cluster_addr": "10.242.43.116:6821\/27623", >> "heartbeat_back_addr": "10.242.43.116:6822\/27623", >> "heartbeat_front_addr": "10.242.43.116:6823\/27623", >> "state": [ >> "exists", >> "up"]}], >> >> output from osd tree: >> # id weight type name up/down reweight >> -1 7.35 root default >> -2 2.8 host rack6-storage-5 >> 0 0.35 osd.0 up 1 >> 1 0.35 osd.1 up 1 >> 2 0.35 osd.2 up 1 >> 3 0.35 osd.3 up 1 >> 4 0.35 osd.4 up 1 >> 5 0.35 osd.5 up 1 >> 6 0.35 osd.6 up 1 >> 7 0.35 osd.7 up 1 >> -3 2.8 host rack6-storage-4 >> 8 0.35 osd.8 up 1 >> 9 0.35 osd.9 up 1 >> 10 0.35 osd.10 up 1 >> 11 0.35 osd.11 up 1 >> 12 0.35 osd.12 up 1 >> 13 0.35 osd.13 up 1 >> 14 0.35 osd.14 up 1 >> 15 0.35 osd.15 up 1 >> -4 1.75 host rack6-storage-6 >> 16 0.35 osd.16 up 1 >> 17 0.35 osd.17 up 1 >> 18 0.35 osd.18 up 1 >> 19 0.35 osd.19 up 1 >> 20 0.35 osd.20 up 1 >> >> Please help me to understand this >> >> -regards, >> Mallikarjun Biradar > > -- Loïc Dachary, Artisan Logiciel Libre
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