Regardless of what the crush tool does, I wouldn't muck around with the IDs of the OSDs. The rest of Celh will probably not handle it well if the crush IDs don't match the OSD numbers. -Greg
On Monday, November 2, 2015, Loris Cuoghi <l...@stella-telecom.fr> wrote: > Le 02/11/2015 12:47, Wido den Hollander a écrit : > >> >> >> On 02-11-15 12:30, Loris Cuoghi wrote: >> >>> Hi All, >>> >>> We're currently on version 0.94.5 with three monitors and 75 OSDs. >>> >>> I've peeked at the decompiled CRUSH map, and I see that all ids are >>> commented with '# Here be dragons!', or more literally : '# do not >>> change unnecessarily'. >>> >>> Now, what would happen if an incautious user would happen to put his >>> chubby fingers on this ids, totally disregarding the warning at the >>> entrance of the cave, and change one of them? >>> >>> Data shuffle? (Relative to the allocation of PGs for the OSD/host/other >>> item?) >>> >>> A *big* data shuffle? (ALL data would need to have its position >>> recalculated, with immediate end-of-the-world data shuffle?) >>> >>> Nothing at all? (And the big fat warning is there only to take fun on >>> the uninstructed ones? Not plausible...) >>> >>> >> Give it a try! Download the CRUSHMap and run tests on it with crushtool: >> >> $ crushtool -i mycrushmap --test --rule 0 --num-rep 3 --show-statistics >> >> Now, change the map, compile it and run again: >> >> $ crushtool -i mycrushmap.new --test --rule 0 --num-rep 3 >> --show-statistics >> >> Check the differences and you get the idea of how much has changed. >> >> Wido >> >> > Thanks Wido ! :) > > Thanks ! >>> >>> Loris >>> _______________________________________________ >>> ceph-users mailing list >>> ceph-users@lists.ceph.com >>> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >>> >> _______________________________________________ >> ceph-users mailing list >> ceph-users@lists.ceph.com >> http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >> >> _______________________________________________ > ceph-users mailing list > ceph-users@lists.ceph.com > http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com >
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