Hi Blairo,
> fio shows 70 MB/s seq read with 4M blocks, libaio, 1 thread, direct.
> > fio seq write 200 MB/s
>
> The fio numbers are from fio running on a CephFS mount I take it?
exactly.
> > # rados bench -t 1 -p test 60 write --no-cleanup
>
> I don't see an rbd test anywhere here...?
>
> I suggest comparing fio on CephFS with fio on rbd (as in using fio's
> rbd ioengine), then at least the application side of your tests is
> constant.
>
I tested four access types:
1. rbd kernel module, xfs, fio-libaio
2. rados bench seq
3. fio-librbd
4. ceph kernel module, fio-libaio
Done tests, no big diference, all methods give 50 to 80 MB/s single
threaded bandwidth.
In my setup I observe rados bench results very similar to kernel module rbd
results while
fio-librbd having 1.5 times lower bandwidth (maybe because it runs in
userspace?)
What can be tuned to improve sequential read?
readahead settings are:
"client_readahead_min": "131072",
"client_readahead_max_bytes": "2097152",
"client_readahead_max_periods": "4",
"rbd_readahead_trigger_requests": "10",
"rbd_readahead_max_bytes": "524288",
"rbd_readahead_disable_after_bytes": "52428800",
--
WBR,
Ilja.
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