简介：
fio是测试IOPS的非常好的工具，用来对硬件进行压力测试和验证，支持13种不同的I/O引擎，包括:sync,mmap, libaio, posixaio, SG v3, splice, null, network, syslet, guasi, solarisaio 等等。
安装fio：
官网网站：http://brick.kernel.dk/snaps/
wget http://brick.kernel.dk/snaps/fio-2.2.10.tar.gz (从官网下载fio的tar包)
tar -zxvf fio-2.2.10.tar.gz （解压）
cd fio-2.2.10
make && make install （安装）
yum install libaio-devel （为了支持同步I/O）
fio分随机读，随机写，顺序读，顺序写，混合随机读写模式。
fio参数：
filename=/dev/sdb #测试文件(设备)的名称，通常选择需要测试的data目录（可以通过冒号分割同时指定多个文件，如filename=/dev/sda:/dev/sdb。）
direct=1 #测试过程绕过机器自带的buffer（缓冲区），使测试结果更真实
rw=randwrite · #测试随机写的I/O
rw=randread #测试随机读的I/O
rw=randrw #测试随机读写的I/O
bs=4k #单次I/O的块文件大小为4K
size=20G #本次测试的文件大小为20G，以每次4K的I/O进行测试
numjobs=30 #本次的测试线程为30个
runtime=600 #测试时间为600秒，如果不写，则一直将20G文件分每次4K写完为止
ioengine=psync #I/O引擎使用psync方式（I/O引擎，现在fio支持19种ioengine。默认值是sync同步阻塞I/O，libaio是Linux的native异步I/O。关于同步异步，阻塞和非阻塞模型可以参考文章“使用异步 I/O 大大提高应用程序的性能”。
http://www.ibm.com/developerworks/cn/linux/l-async/）
group_reporting #关于显示结果的，汇总每个进程的信息
name #指定job的名字，在命令行中表示新启动一个job。
iodepth #如果ioengine采用异步方式，该参数表示一批提交保持的io单元数。（该参数可参考文章“Fio压测工具和io队列深度理解和误区”。http://blog.yufeng.info/archives/2104）
thread #线程
fio实例：
随机读4K：
fio -filename=/dev/sdb:/dev/sdc:/dev/sdd -direct=1 -iodepth=16 -thread -rw=randread -ioengine=libaio -bs=4k -size=20G -numjobs=30 -runtime=600 -group_reporting -name=mytest
随机写4K：
fio -filename=/dev/sdb:/dev/sdc:/dev/sdd -direct=1 -iodepth=16 -thread -rw=randwrite -ioengine=libaio -bs=4k -size=20G -numjobs=30 -runtime=600 -group_reporting -name=mytest
顺序读1M：
fio -filename=/dev/sdb:/dev/sdc:/dev/sdd -direct=1 -iodepth=16 -thread -rw=read -ioengine=libaio -bs=1M -size=20G -numjobs=30 -runtime=600 -group_reporting -name=mytest
顺序写1M：
fio -filename=/dev/sdb:/dev/sdc:/dev/sdd -direct=1 -iodepth=16 -thread -rw=write -ioengine=libaio -bs=1M -size=20G -numjobs=30 -runtime=600 -group_reporting -name=mytest
混合随机读写：
fio -filename=/dev/sdb:/dev/sdc:/dev/sdd -direct=1 -iodepth 1 -thread -rw=randrw -rwmixread=70 -ioengine=psync -bs=16k -size=200G -numjobs=30 -runtime=100 -group_reporting -name=mytest -ioscheduler=noop
实例测试：
注：主要关注结果用橙色标出
4k随机读：
[root@localhost ~]# fio -filename=/dev/sda:/dev/sdb:/dev/sdc -direct=1 -iodepth 1 -thread -rw=randread -ioengine=libaio -bs=4k -size=20G -numjobs=30 -runtime=100 -group_reporting -name=mytest mytest: (g=0): rw=randread, bs=(R) 4096B-4096B, (W) 4096B-4096B, (T) 4096B-4096B, ioengine=libaio, iodepth=1 ... fio-2.21 Starting 30 threads Jobs: 30 (f=90): [r(30)][100.0%][r=11.2MiB/s,w=0KiB/s][r=2875,w=0 IOPS][eta 00m:00s] mytest: (groupid=0, jobs=30): err= 0: pid=26843: Thu Jun 22 09:47:06 2017 read: IOPS=2756, BW=10.8MiB/s (11.3MB/s)(1077MiB/100033msec) slat (usec): min=6, max=1137, avg=21.55, stdev= 9.74 clat (usec): min=304, max=675395, avg=10853.67, stdev=12909.46 lat (usec): min=334, max=675425, avg=10875.94, stdev=12909.57 clat percentiles (usec): | 1.00th=[ 1272], 5.00th=[ 2480], 10.00th=[ 3536], 20.00th=[ 5216], | 30.00th=[ 6560], 40.00th=[ 7840], 50.00th=[ 9152], 60.00th=[10560], | 70.00th=[12224], 80.00th=[14144], 90.00th=[17280], 95.00th=[21632], | 99.00th=[46336], 99.50th=[66048], 99.90th=[136192], 99.95th=[179200], | 99.99th=[651264] bw ( KiB/s): min= 16, max= 553, per=0.00%, avg=369.92, stdev=100.81 lat (usec) : 500=0.11%, 750=0.12%, 1000=0.27% lat (msec) : 2=2.59%, 4=9.55%, 10=43.26%, 20=37.74%, 50=5.51% lat (msec) : 100=0.63%, 250=0.20%, 500=0.01%, 750=0.01% cpu : usr=0.09%, sys=0.32%, ctx=275751, majf=0, minf=69 IO depths : 1=100.0%, 2=0.0%, 4=0.0%, 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 rwt: total=275725,0,0, short=0,0,0, dropped=0,0,0 latency : target=0, window=0, percentile=100.00%, depth=1 Run status group 0 (all jobs): READ: bw=10.8MiB/s (11.3MB/s), 10.8MiB/s-10.8MiB/s (11.3MB/s-11.3MB/s), io=1077MiB (1129MB), run=100033-100033msec Disk stats (read/write): sda: ios=91772/0, merge=0/0, ticks=1014292/0, in_queue=1014284, util=92.52% sdb: ios=91762/0, merge=0/0, ticks=923274/0, in_queue=923228, util=84.34% sdc: ios=91745/0, merge=0/0, ticks=1042310/0, in_queue=1043251, util=91.21%
混合随机读写：
[root@localhost ~]# fio -filename=/dev/sda:/dev/sdb:/dev/sdc -direct=1 -iodepth 1 -thread -rw=randrw -ioengine=libaio -bs=4k -size=20G -numjobs=30 -runtime=100 -group_reporting -name=mytest mytest: (g=0): rw=randrw, bs=(R) 4096B-4096B, (W) 4096B-4096B, (T) 4096B-4096B, ioengine=libaio, iodepth=1 ... fio-2.21 Starting 30 threads Jobs: 30 (f=90): [m(30)][100.0%][r=404KiB/s,w=464KiB/s][r=101,w=116 IOPS][eta 00m:00s] mytest: (groupid=0, jobs=30): err= 0: pid=26892: Thu Jun 22 09:57:34 2017 read: IOPS=86, BW=345KiB/s (353kB/s)(33.7MiB/100117msec) slat (usec): min=9, max=168, avg=30.70, stdev=11.21 clat (usec): min=464, max=764655, avg=50031.54, stdev=79240.40 lat (usec): min=486, max=764705, avg=50063.31, stdev=79240.09 clat percentiles (usec): | 1.00th=[ 756], 5.00th=[ 1272], 10.00th=[ 1688], 20.00th=[ 2672], | 30.00th=[ 5280], 40.00th=[ 8512], 50.00th=[10944], 60.00th=[23424], | 70.00th=[45824], 80.00th=[86528], 90.00th=[154624], 95.00th=[216064], | 99.00th=[350208], 99.50th=[415744], 99.90th=[577536], 99.95th=[651264], | 99.99th=[765952] bw ( KiB/s): min= 7, max= 81, per=0.01%, avg=18.68, stdev=12.27 write: IOPS=85, BW=344KiB/s (352kB/s)(33.6MiB/100117msec) slat (usec): min=10, max=914, avg=34.27, stdev=15.34 clat (msec): min=3, max=1779, avg=297.95, stdev=232.05 lat (msec): min=3, max=1779, avg=297.99, stdev=232.05 clat percentiles (msec): | 1.00th=[ 9], 5.00th=[ 27], 10.00th=[ 56], 20.00th=[ 109], | 30.00th=[ 153], 40.00th=[ 194], 50.00th=[ 239], 60.00th=[ 297], | 70.00th=[ 367], 80.00th=[ 461], 90.00th=[ 611], 95.00th=[ 758], | 99.00th=[ 1045], 99.50th=[ 1221], 99.90th=[ 1434], 99.95th=[ 1516], | 99.99th=[ 1778] bw ( KiB/s): min= 7, max= 48, per=0.00%, avg=13.50, stdev= 6.61 lat (usec) : 500=0.02%, 750=0.48%, 1000=0.67% lat (msec) : 2=5.84%, 4=5.92%, 10=10.74%, 20=7.24%, 50=9.34% lat (msec) : 100=10.07%, 250=23.98%, 500=17.14%, 750=5.98%, 1000=1.94% lat (msec) : 2000=0.64% cpu : usr=0.01%, sys=0.03%, ctx=17375, majf=0, minf=39 IO depths : 1=100.0%, 2=0.0%, 4=0.0%, 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 rwt: total=8637,8610,0, short=0,0,0, dropped=0,0,0 latency : target=0, window=0, percentile=100.00%, depth=1 Run status group 0 (all jobs): READ: bw=345KiB/s (353kB/s), 345KiB/s-345KiB/s (353kB/s-353kB/s), io=33.7MiB (35.4MB), run=100117-100117msec WRITE: bw=344KiB/s (352kB/s), 344KiB/s-344KiB/s (352kB/s-352kB/s), io=33.6MiB (35.3MB), run=100117-100117msec Disk stats (read/write): sda: ios=2965/2885, merge=0/0, ticks=155272/883659, in_queue=1040854, util=100.00% sdb: ios=3068/2826, merge=0/0, ticks=131988/846676, in_queue=981819, util=99.66% sdc: ios=3091/2870, merge=0/0, ticks=150587/826686, in_queue=984877, util=99.90%
硬盘性能指标：
顺序读写 （吞吐量，常用单位为MB/s）：文件在硬盘上存储位置是连续的。
适用场景：大文件拷贝（比如视频音乐）。速度即使很高，对数据库性能也没有参考价值。
4K随机读写 （IOPS，常用单位为次）：在硬盘上随机位置读写数据，每次4KB。
适用场景：操作系统运行、软件运行、数据库。