fio problems

[Danny Kukawka <dkukawka@suse.de>]

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Hi,

we try to run fio against raw RBD devices on a ceph cluster. Here are
the parameter we use to run fio:

[test]
filename=/dev/rbd0
time_based
runtime=3h
rw=randrw
rwmixread=80
rwmixwrite=20
blocksize_range=4k-1024k
ioengine=libaio
iodepth=64
direct=1
verify=crc32c-intel
verify_fatal=1
verify_async=16
lockfile=exclusive

We see some problems:

1) fio reports higher READ speeds than the used 1Gbit network interface
could provide (the interface isn't even working to capacity in this
situation). That happens if we use --rwmixread/rwmixwrite:

 READ: io=91560MB, aggrb=156206KB/s, minb=159955KB/s,
        maxb=159955KB/s, mint=600216msec, maxt=600216msec
 WRITE: io=22944MB, aggrb=39143KB/s, minb=40083KB/s, maxb=40083KB/s,
        mint=600216msec, maxt=600216msec

2) fio 2.0.6 and also the current git tends to fail with this error:

   fio 2.0.6
   Starting 1 process
   fio: iolog.c:242: log_io_piece: Assertion `ipo->len == __ipo->len'
   failed.:08m:31s]

It seems that we can prevent it when we use the --size parameter, but we
would like to prevent the usage of the parameter, if possible

3) fio always reports minb == maxb and aggrb < minb as you can see
above. From my understanding this would be false info.

4) If we define rw=randrw, rwmixread=80, rwmixwrite=20 and the verify
options, what does the READ process if there isn't enough data written
out yet? Which data does READ read and verify?

Thanks and Regards,

Danny
-- 
Danny Kukawka
 SUSE LINUX Products GmbH
  Maxfeldstrasse 5, D-90409 Nuremberg, Germany
  GF: Jeff Hawn,Jennifer Guild,Felix Imendörffer,HRB16746 (AG Nürnberg)


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