> Thanks for chiming in. Unfortunately, it doesn't really help answering my questions either. > > Concurrency: A system like ceph that hashes data into PGs translates any IO into random IO anyways. So it's irrelevant for spinners, they have to seek anyways and the degree of parallelism doesn't matter on systems with sufficient load. In addition, for OSDs at least up to pacific the kv_sync_thread serializes everything (writes only?) anyways, so whatever concurrency more PGs add, this thread puts it back in sequence. I could imagine that each PG had a certain amount of meta-operations, like logging, database vacuuming or reindexing and so on that happens at some intervals regardless of if you access objects or not. In that case, the PG meta ops would scale with the number of PGs in the OSD but as you state above not with the number of objects, which of course stays more or less the same. If this was true, then going from 100 to 1000 PGs would make these ops upto 10x more while object IO would stay the same. -- May the most significant bit of your life be positive. _______________________________________________ ceph-users mailing list -- ceph-users@xxxxxxx To unsubscribe send an email to ceph-users-leave@xxxxxxx
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