gistfile1.txt

   52  sudo mdadm --create /dev/md0 -l 0 -n 4 /dev/sdi1 /dev/sdj1 /dev/sdk1 /dev/sdl1
   53  sudo mkfs.xfs /dev/md0
   54  sudo mount /dev/md0 /mnt/sdi
   55  cd /mnt/sdi
   56  ls
   57  sudo fio ~/rw5050.fio 

mdraid0-xfs-ioswitchx4.txt

atobey@zorak /mnt/sdi $ sudo fio ~/rw5050.fio
rw5050: (g=0): rw=randrw, bs=4K-4K/4K-4K/4K-4K, ioengine=libaio, iodepth=32
...
fio-2.1.9
Starting 4 processes
rw5050: Laying out IO file(s) (1 file(s) / 25600MB)
rw5050: Laying out IO file(s) (1 file(s) / 25600MB)
rw5050: Laying out IO file(s) (1 file(s) / 25600MB)
rw5050: Laying out IO file(s) (1 file(s) / 25600MB)
Jobs: 3 (f=3): [ff_f] [100.0% done] [0KB/0KB/0KB /s] [0/0/0 iops] [eta 00m:00s]
rw5050: (groupid=0, jobs=4): err= 0: pid=1011: Tue Jun 17 20:20:23 2014
  Description  : ["random 50/50"]
  read : io=108895MB, bw=185847KB/s, iops=46461, runt=600004msec
    slat (usec): min=26, max=6356, avg=65.39, stdev=102.89
    clat (usec): min=0, max=682139, avg=1357.79, stdev=1971.76
     lat (usec): min=76, max=682173, avg=1423.35, stdev=1975.36
    clat percentiles (usec):
     |  1.00th=[  137],  5.00th=[  191], 10.00th=[  251], 20.00th=[  374],
     | 30.00th=[  502], 40.00th=[  668], 50.00th=[  884], 60.00th=[ 1176],
     | 70.00th=[ 1608], 80.00th=[ 2224], 90.00th=[ 2992], 95.00th=[ 3728],
     | 99.00th=[ 5536], 99.50th=[ 7968], 99.90th=[17280], 99.95th=[20352],
     | 99.99th=[25728]
    bw (KB  /s): min=    4, max=59448, per=25.02%, avg=46496.27, stdev=4360.87
  write: io=108943MB, bw=185928KB/s, iops=46481, runt=600004msec
    slat (usec): min=26, max=6358, avg=65.72, stdev=103.52
    clat (usec): min=0, max=680881, avg=1247.52, stdev=2001.07
     lat (usec): min=55, max=680917, avg=1313.42, stdev=2004.50
    clat percentiles (usec):
     |  1.00th=[   87],  5.00th=[  153], 10.00th=[  197], 20.00th=[  302],
     | 30.00th=[  430], 40.00th=[  580], 50.00th=[  772], 60.00th=[ 1048],
     | 70.00th=[ 1432], 80.00th=[ 2024], 90.00th=[ 2832], 95.00th=[ 3632],
     | 99.00th=[ 5408], 99.50th=[ 7776], 99.90th=[17280], 99.95th=[20352],
     | 99.99th=[25728]
    bw (KB  /s): min=    4, max=59592, per=25.02%, avg=46516.07, stdev=4355.41
    lat (usec) : 2=0.03%, 4=0.05%, 10=0.01%, 20=0.01%, 50=0.07%
    lat (usec) : 100=0.59%, 250=11.89%, 500=19.81%, 750=14.04%, 1000=9.94%
    lat (msec) : 2=21.84%, 4=18.06%, 10=3.34%, 20=0.28%, 50=0.05%
    lat (msec) : 100=0.01%, 750=0.01%
  cpu          : usr=1.69%, sys=12.11%, ctx=40033328, majf=0, minf=53671
  IO depths    : 1=0.0%, 2=0.0%, 4=0.0%, 8=0.0%, 16=0.1%, 32=100.8%, >=64=0.0%
     submit    : 0=0.0%, 4=0.0%, 8=0.0%, 16=100.0%, 32=0.0%, 64=0.0%, >=64=0.0%
     complete  : 0=0.0%, 4=0.0%, 8=0.0%, 16=100.0%, 32=0.0%, 64=0.0%, >=64=0.0%
     issued    : total=r=27877096/w=27889384/d=0, short=r=0/w=0/d=0
     latency   : target=0, window=0, percentile=100.00%, depth=32

Run status group 0 (all jobs):
   READ: io=108895MB, aggrb=185846KB/s, minb=185846KB/s, maxb=185846KB/s, mint=600004msec, maxt=600004msec
  WRITE: io=108943MB, aggrb=185928KB/s, minb=185928KB/s, maxb=185928KB/s, mint=600004msec, maxt=600004msec

Disk stats (read/write):
    md0: ios=28108078/28127429, merge=0/0, ticks=0/0, in_queue=0, util=0.00%, aggrios=7027005/7031877, aggrmerge=14/19, aggrticks=7008906/6324628, aggrin_queue=13332993, aggrutil=90.95%
  sdi: ios=7029934/7028869, merge=11/28, ticks=7502050/7304213, in_queue=14806603, util=90.85%
  sdj: ios=7025591/7038437, merge=18/13, ticks=7486180/7299860, in_queue=14785483, util=90.95%
  sdk: ios=7024992/7030193, merge=12/21, ticks=7328173/7127733, in_queue=14456030, util=90.34%
  sdl: ios=7027505/7030011, merge=15/17, ticks=5719223/3566707, in_queue=9283857, util=85.48%