Since fio /dev/rbd0 sync=1 works well, it doesn't matter with ceph server, just related to librbd (rbd_aio_flush) implement?
2016-02-26 14:50 GMT+08:00 Huan Zhang <[email protected]>: > rbd engine with fsync=1 seems stuck. > Jobs: 1 (f=1): [w(1)] [0.0% done] [0KB/0KB/0KB /s] [0/0/0 iops] [eta > 1244d:10h:39m:18s] > > But fio using /dev/rbd0 sync=1 direct=1 ioengine=libaio iodepth=64, get > very high iops ~35K, similar to direct wirte. > > I'm confused with that result, IMHO, ceph could just ignore the sync cache > command since it always use sync write to journal, right? > > Why we get so bad sync iops, how ceph handle it? > Very appreciated to get your reply! > > 2016-02-25 22:44 GMT+08:00 Jason Dillaman <[email protected]>: > >> > 35K IOPS with ioengine=rbd sounds like the "sync=1" option doesn't >> actually >> > work. Or it's not touching the same object (but I wonder whether write >> > ordering is preserved at that rate?). >> >> The fio rbd engine does not support "sync=1"; however, it should support >> "fsync=1" to accomplish roughly the same effect. >> >> Jason >> > >
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