On 20 December 2015 at 22:47, Yan, Zheng <ukernel@xxxxxxxxx> wrote:
fio tests AIO performance in this case. cephfs does not handle AIO>> ---------------------------------------------------------------
>>
properly, AIO is actually SYNC IO. that's why cephfs is so slow in
this case.
Regards
Yan, Zheng
OK, so i changed fio engine to 'sync' for the comparison of a single underlying osd vs the cephfs.
the cephfs w/ sync is ~ 115iops / ~500KB/s.
the underlying osd storage w/ sync is 6500 iops/270MB/s.
I also don't think this explains why cephfs-fuse faster (~5x faster, but still ~100x slower than it should be).
If i get rid of fio and use tried-and-true dd:
time dd if=/dev/zero of=rw.data bs=256k count=10000
on the underlying osd storage shows 426MB/s.
on the cephfs, it gets 694MB/s.
hmm.
so i guess my 'lag' issue of slow requests is unrelated and is my real problem.
_______________________________________________ ceph-users mailing list ceph-users@xxxxxxxxxxxxxx http://lists.ceph.com/listinfo.cgi/ceph-users-ceph.com
