scylla - scylla_setup からのディスク iops iotune study my disk is different from fio test data

Question

scylla_setup を使用する場合、iotune の調査結果は次のとおりです。

Measuring sequential write bandwidth: 473 MB/s
Measuring sequential read bandwidth: 499 MB/s
Measuring random write IOPS: 1902 IOPS
Measuring random read IOPS: 1999 IOPS

iops は 1900-2000 で、fio を使用する場合、

fio --randrepeat=1 --ioengine=libaio --direct=1 --gtod_reduce=1 --name=test --filename=/dev/sdc1 --bs=4k --iodepth=64 --size=4G --readwrite=randrw --rwmixread=75

結果は

test: (groupid=0, jobs=1): err= 0: pid=11697: Wed Jun 26 08:58:13 2019
   read: IOPS=47.6k, BW=186MiB/s (195MB/s)(3070MiB/16521msec)
   bw (  KiB/s): min=187240, max=192136, per=100.00%, avg=190278.42, stdev=985.15, samples=33
   iops        : min=46810, max=48034, avg=47569.61, stdev=246.38, samples=33
  write: IOPS=15.9k, BW=62.1MiB/s (65.1MB/s)(1026MiB/16521msec)
   bw (  KiB/s): min=62656, max=65072, per=100.00%, avg=63591.52, stdev=590.96, samples=33
   iops        : min=15664, max=16268, avg=15897.88, stdev=147.74, samples=33
  cpu          : usr=4.82%, sys=12.81%, ctx=164053, majf=0, minf=23
  IO depths    : 1=0.1%, 2=0.1%, 4=0.1%, 8=0.1%, 16=0.1%, 32=0.1%, >=64=100.0%
     submit    : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0%
     complete  : 0=0.0%, 4=100.0%, 8=0.0%, 16=0.0%, 32=0.0%, 64=0.1%, >=64=0.0%
     issued rwt: total=785920,262656,0, short=0,0,0, dropped=0,0,0
     latency   : target=0, window=0, percentile=100.00%, depth=64

Run status group 0 (all jobs):
   READ: bw=186MiB/s (195MB/s), 186MiB/s-186MiB/s (195MB/s-195MB/s), io=3070MiB (3219MB), run=16521-16521msec
  WRITE: bw=62.1MiB/s (65.1MB/s), 62.1MiB/s-62.1MiB/s (65.1MB/s-65.1MB/s), io=1026MiB (1076MB), run=16521-16521msec

Disk stats (read/write):
  sdc: ios=780115/260679, merge=0/0, ticks=792798/230409, in_queue=1023170, util=99.47%

読み取り iops は 46000 ～ 48000、書き込み iops は 15000 ～ 16000