fio is a tool that will spawn a number of threads or processes doing a particular type of I/O action as specified by the user. The typical use of fio is to write a job file matching the I/O load one wants to simulate.
相对而言，dd只是测试磁盘的物理性能，并且只是测试的磁盘顺序读写的带宽。但实际上磁盘性能的瓶颈往往是IOPS，这个是dd无法测试出来的。
Fio可以按照使用者的需求启动多个线程模拟各种不同的IO操作，测试出有文件系统的磁盘在实际的随机读写的工作模式下所能承受的实际压力。
下载
fio 下载:
[http://freshmeat.net/projects/fio/]
fio 手册:
[http://linux.die.net/man/1/fio]
fio 文章：
[http://www.linux.com/archive/feature/131063]
make & make install 即可
如果出现下面的错误：
CC gettime.o
In file included from fio.h:23,
from gettime.c:8:
os/os.h:15:20: error: libaio.h: No such file or directory
In file included from gettime.c:8:
fio.h:119: error: field 'iocb' has incomplete type
make: *** [gettime.o] Error 1安装这两个包：
sudo apt-get install libaio1 libaio-dev
测试
在source code里面自带有测试的fio脚本，使用fio [filename] 即可进行测试，下面的结果是测试vmware 7.0中,NILFS文件系统随机读的测试结果：
rex@rexvm:~/下载/fio-1.36/examples$ fio aio-read file1: (g=0): rw=randread, bs=128K-128K/128K-128K, ioengine=libaio, iodepth=4 file2: (g=0): rw=randread, bs=128K-128K/128K-128K, ioengine=libaio, iodepth=32 file3: (g=0): rw=randread, bs=128K-128K/128K-128K, ioengine=libaio, iodepth=8 file4: (g=0): rw=randread, bs=128K-128K/128K-128K, ioengine=libaio, iodepth=16 Starting 4 processes file1: Laying out IO file(s) (1 file(s) / 512MB) file2: Laying out IO file(s) (1 file(s) / 512MB) file3: Laying out IO file(s) (1 file(s) / 512MB) file4: Laying out IO file(s) (1 file(s) / 512MB) Jobs: 1 (f=1): [r___] [100.0% done] [86426K/0K /s] [659/0 iops] [eta 00m:00s] file1: (groupid=0, jobs=1): err= 0: pid=8637 read : io=524288KB, bw=24611KB/s, iops=192, runt= 21303msec slat (usec): min=123, max=57781, avg=3508.71, stdev=8292.79 clat (usec): min=47, max=388155, avg=17137.44, stdev=43573.89 bw (KB/s) : min=10069, max=75520, per=23.88%, avg=23504.13, stdev=12992.39 cpu : usr=0.15%, sys=20.28%, ctx=672, majf=0, minf=156 IO depths : 1=0.1%, 2=0.1%, 4=99.9%, 8=0.0%, 16=0.0%, 32=0.0%, >=64=0.0% 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=0.0%, >=64=0.0% issued r/w: total=4096/0, short=0/0 lat (usec): 50=2.88%, 100=24.56%, 250=1.22%, 500=0.46%, 750=4.10% lat (usec): 1000=9.25% lat (msec): 2=14.23%, 4=15.43%, 10=1.05%, 20=2.95%, 50=16.33% lat (msec): 100=2.95%, 250=3.61%, 500=0.95% file2: (groupid=0, jobs=1): err= 0: pid=8638 read : io=524288KB, bw=26222KB/s, iops=204, runt= 19994msec slat (usec): min=123, max=81954, avg=4452.41, stdev=9360.67 clat (msec): min=7, max=710, avg=148.20, stdev=64.75 bw (KB/s) : min= 168, max=34048, per=27.30%, avg=26875.55, stdev=5675.16 cpu : usr=0.10%, sys=24.71%, ctx=678, majf=0, minf=1052 IO depths : 1=0.1%, 2=0.1%, 4=0.1%, 8=0.2%, 16=0.4%, 32=99.2%, >=64=0.0% 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=0.1%, 64=0.0%, >=64=0.0% issued r/w: total=4096/0, short=0/0 lat (msec): 10=0.10%, 20=0.12%, 50=0.71%, 100=9.42%, 250=83.89% lat (msec): 500=5.44%, 750=0.32% file3: (groupid=0, jobs=1): err= 0: pid=8639 read : io=524288KB, bw=26203KB/s, iops=204, runt= 20009msec slat (usec): min=124, max=158833, avg=4322.76, stdev=9381.58 clat (usec): min=47, max=457767, avg=34494.35, stdev=47974.57 bw (KB/s) : min=13810, max=41306, per=27.00%, avg=26578.39, stdev=5382.38 cpu : usr=0.20%, sys=23.35%, ctx=654, majf=0, minf=284 IO depths : 1=0.1%, 2=0.1%, 4=0.1%, 8=99.8%, 16=0.0%, 32=0.0%, >=64=0.0% 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=0.1%, 16=0.0%, 32=0.0%, 64=0.0%, >=64=0.0% issued r/w: total=4096/0, short=0/0 lat (usec): 50=0.32%, 100=2.37%, 250=0.20%, 500=0.07%, 750=1.03% lat (usec): 1000=2.42% lat (msec): 2=4.91%, 4=9.64%, 10=9.94%, 20=5.91%, 50=49.68% lat (msec): 100=7.32%, 250=5.08%, 500=1.12% file4: (groupid=0, jobs=1): err= 0: pid=8640 read : io=524288KB, bw=26301KB/s, iops=205, runt= 19934msec slat (usec): min=124, max=65601, avg=4483.65, stdev=9360.13 clat (msec): min=1, max=459, avg=72.36, stdev=51.90 bw (KB/s) : min= 1237, max=39936, per=27.08%, avg=26655.42, stdev=5750.57 cpu : usr=0.14%, sys=24.12%, ctx=668, majf=0, minf=540 IO depths : 1=0.1%, 2=0.1%, 4=0.1%, 8=0.2%, 16=99.6%, 32=0.0%, >=64=0.0% 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=0.1%, 32=0.0%, 64=0.0%, >=64=0.0% issued r/w: total=4096/0, short=0/0 lat (msec): 2=0.02%, 4=0.68%, 10=0.78%, 20=1.17%, 50=27.51% lat (msec): 100=56.42%, 250=11.06%, 500=2.34% Run status group 0 (all jobs): READ: io=2048MB, aggrb=98443KB/s, minb=25201KB/s, maxb=26932KB/s, mint=19934msec, maxt=21303msec Disk stats (read/write): sdb: ios=16543/3236, merge=0/0, ticks=234540/23416, in_queue=257840, util=37.67%