1、fio 简单介绍
fio 磁盘性能测试工具，磁盘IO是检查磁盘性能的重要指标，可以按照负载情况分成顺序读写、随机读写两大类
fio最初是用来节省为特定负载写专门测试程序，或是进行性能测试，或是找到和重现bug的时间。写这么一个测试应用是非常浪费时间的。因此需要一个工具来模拟给定的io负载，而不用重复的写一个又一个的特定的测试程序。但是test负载很难定义。因为可能会产生很多进程或线程，他们每一个都用他们自己的方式产生io。fio需要足够灵活得来模拟这些case
2、磁盘读写原理与顺序/随机读写说明以及区别
许多小伙伴不太明白顺序读写和随机读写的意思和区别（比如我，查阅了不少资料做了以下简单的描述）
（1）磁盘读写原理
信息存储在硬盘里，打开也看不见里面有任何东西只有些盘片。如果把盘片放大，会看见盘片表面凹凸不平，凸起的地方被磁化，凹的地方是没有被磁化；凸起的地方代表数字1（磁化为1），凹的地方代表数字0。因此硬盘可以以二进制来存储表示文字、图片等信息。
（2）顺序读写和随机读写
顺序读写：指的是本次 I/O 给出的初始扇区地址和上一次 I/O 的结束扇区地址是完全连续或者相隔不多的。反之，如果相差很大，则算作一次随机 I/O。
随机读写：随机I/O可能是因为磁盘碎片导致磁盘空间不连续，或者当前block空间小于文件大小导致的。
SSD固态盘主要看的就是随机读写性能-（由控制单元和固态存储单元（DRAM或FLASH芯片）组成，存储单元负责存储数据，控制单元负责读取、写入数据。由于固态硬盘没有普通硬盘的机械结构，也不存在机械硬盘的寻道问题）
SAS机械硬盘主要看的是顺序读写性能-（数据是存储的扇区的，读写是依靠磁头的摆动寻址的。顺序读写主要时间花费在了传输时间，随机读写需要多次寻道和旋转延迟。）
（3）顺序读写与随机读写区别
顺序读写：文件指针只能从头移动到尾。
随机读写：文件指针可以随意移动，根据需要。
连续读写比随机读写效率高
因为在做连续读写的时候，磁头几乎不用换道或者换道的时间很短；
而对于随机读写，如果这个读写很多的话，会导致磁头不停地换道，造成效率的降低。
3、参数说明（更多参数详见“fio --help”）
-filename=/dev/sdb1 测试文件名称，通常选择需要测试的盘的data目录。 只能是分区，不能是目录，会破坏数据
-direct=1 测试过程绕过机器自带的buffer。使测试结果更真实。
-rw=randrw 测试随机写和读的I/O
-rw=rw/readwrite 测试顺序读写的I/O
-rw=read 顺序读
-rw=write 顺序写
-rw=randread 随机读
-rw=randwrite 随机写
-iodepth=1 队列深度，只有使用libaio时才有意义，这是一个可以影响IOPS的参数，通常情况下为1。
-ioengine=psync/libaio io引擎使用pync方式
-bs=4k 单次io的块文件大小为4k (单次IO越小的时候，单次IO所耗费的时间也越少，相应的IOPS也就越大)
-size=2G 测试文件大小为2g，以每次4k的io进行测试,此大小不能超过filename的大小，否则会报错。
-numjobs=10 测试线程为10.
-runtime=10 测试时间为10秒，如果不写则一直将2g文件分4k每次写完为止。
-lockmem=1g 只使用1g内存进行测试。
-rwmixwrite=30 在混合读写的模式下，写占30%
-group_reporting 关于显示结果的，汇总每个进程的信息。
-name=name 直接测试读会在测试设备写入name.*文件
-output=rw.txt 将输出内容写入文件
4、测试范例 （视情况自行选择参数并更改）
（1）顺序读
[root@centos7 test]# fio -fimename=/dev/sdc1 -direct=1 -rw=read -iodepth=1 -ioengine=psync -bs=4k -size=2G -numjobs=1 -runtime=10 -group_reporting -name=name
name: (g=0): rw=read, bs=4K-4K/4K-4K/4K-4K, ioengine=psync, iodepth=1
fio-2.1.10
Starting 1 process
name: Laying out IO file(s) (1 file(s) / 2048MB)
Jobs: 1 (f=1): [R] [100.0% done] [53528KB/0KB/0KB /s] [13.4K/0/0 iops] [eta 00m:00s]
name: (groupid=0, jobs=1): err= 0: pid=15754: Sun May 9 00:04:40 2021
read : io=608940KB, bw=60888KB/s, iops=15221, runt= 10001msec
clat (usec): min=42, max=634, avg=64.26, stdev=13.58
lat (usec): min=42, max=635, avg=64.40, stdev=13.58
clat percentiles (usec):
| 1.00th=[ 47], 5.00th=[ 50], 10.00th=[ 51], 20.00th=[ 52],
| 30.00th=[ 53], 40.00th=[ 56], 50.00th=[ 66], 60.00th=[ 69],
| 70.00th=[ 72], 80.00th=[ 74], 90.00th=[ 77], 95.00th=[ 81],
| 99.00th=[ 107], 99.50th=[ 124], 99.90th=[ 171], 99.95th=[ 195],
| 99.99th=[ 266]
bw (KB /s): min=51072, max=74128, per=100.00%, avg=61282.95, stdev=8940.17
lat (usec) : 50=3.15%, 100=95.56%, 250=1.28%, 500=0.01%, 750=0.01%
cpu : usr=0.07%, sys=75.35%, ctx=140335, majf=0, minf=28
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 : total=r=152235/w=0/d=0, short=r=0/w=0/d=0
latency : target=0, window=0, percentile=100.00%, depth=1
Run status group 0 (all jobs):
READ: io=608940KB, aggrb=60887KB/s, minb=60887KB/s, maxb=60887KB/s, mint=10001msec, maxt=10001msec
Disk stats (read/write):
sdc: ios=149199/2, merge=0/1, ticks=7981/0, in_queue=7978, util=80.90%（2）顺序写
[root@centos7 test]# fio -fimename=/dev/sdc1 -direct=1 -rw=write -iodepth=1 -ioengine=psync -bs=4k -size=2G -numjobs=1 -runtime=10 -group_reporting -name=name
name: (g=0): rw=write, bs=4K-4K/4K-4K/4K-4K, ioengine=psync, iodepth=1
fio-2.1.10
Starting 1 process
Jobs: 1 (f=1): [W] [100.0% done] [0KB/48488KB/0KB /s] [0/12.2K/0 iops] [eta 00m:00s]
name: (groupid=0, jobs=1): err= 0: pid=15893: Sun May 9 00:07:27 2021
write: io=527800KB, bw=52775KB/s, iops=13193, runt= 10001msec
clat (usec): min=53, max=751, avg=74.34, stdev=16.13
lat (usec): min=53, max=751, avg=74.52, stdev=16.14
clat percentiles (usec):
| 1.00th=[ 57], 5.00th=[ 58], 10.00th=[ 59], 20.00th=[ 60],
| 30.00th=[ 62], 40.00th=[ 64], 50.00th=[ 74], 60.00th=[ 80],
| 70.00th=[ 83], 80.00th=[ 87], 90.00th=[ 90], 95.00th=[ 94],
| 99.00th=[ 123], 99.50th=[ 141], 99.90th=[ 187], 99.95th=[ 213],
| 99.99th=[ 422]
bw (KB /s): min=42824, max=62568, per=100.00%, avg=52800.00, stdev=6626.28
lat (usec) : 100=97.08%, 250=2.89%, 500=0.02%, 750=0.01%, 1000=0.01%
cpu : usr=0.05%, sys=85.36%, ctx=80042, majf=0, minf=29
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 : total=r=0/w=131950/d=0, short=r=0/w=0/d=0
latency : target=0, window=0, percentile=100.00%, depth=1
Run status group 0 (all jobs):
WRITE: io=527800KB, aggrb=52774KB/s, minb=52774KB/s, maxb=52774KB/s, mint=10001msec, maxt=10001msec
Disk stats (read/write):
sdc: ios=0/130571, merge=0/1, ticks=0/8390, in_queue=8388, util=83.89%（3）随机读
[root@centos7 test]# fio -fimename=/dev/sdc1 -direct=1 -rw=randread -iodepth=1 -ioengine=psync -bs=4k -size=2G -numjobs=1 -runtime=10 -group_reporting -name=name
name: (g=0): rw=randread, bs=4K-4K/4K-4K/4K-4K, ioengine=psync, iodepth=1
fio-2.1.10
Starting 1 process
Jobs: 1 (f=1): [r] [100.0% done] [53036KB/0KB/0KB /s] [13.3K/0/0 iops] [eta 00m:00s]
name: (groupid=0, jobs=1): err= 0: pid=15974: Sun May 9 00:09:00 2021
read : io=550584KB, bw=55053KB/s, iops=13763, runt= 10001msec
clat (usec): min=45, max=2140, avg=71.00, stdev=17.94
lat (usec): min=45, max=2141, avg=71.13, stdev=17.95
clat percentiles (usec):
| 1.00th=[ 48], 5.00th=[ 51], 10.00th=[ 52], 20.00th=[ 56],
| 30.00th=[ 67], 40.00th=[ 70], 50.00th=[ 73], 60.00th=[ 74],
| 70.00th=[ 77], 80.00th=[ 79], 90.00th=[ 83], 95.00th=[ 89],
| 99.00th=[ 110], 99.50th=[ 131], 99.90th=[ 181], 99.95th=[ 213],
| 99.99th=[ 812]
bw (KB /s): min=46928, max=69160, per=99.99%, avg=55045.47, stdev=6973.14
lat (usec) : 50=2.19%, 100=96.14%, 250=1.64%, 500=0.02%, 750=0.01%
lat (usec) : 1000=0.01%
lat (msec) : 2=0.01%, 4=0.01%
cpu : usr=0.09%, sys=78.34%, ctx=121541, majf=0, minf=28
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 : total=r=137646/w=0/d=0, short=r=0/w=0/d=0
latency : target=0, window=0, percentile=100.00%, depth=1
Run status group 0 (all jobs):
READ: io=550584KB, aggrb=55052KB/s, minb=55052KB/s, maxb=55052KB/s, mint=10001msec, maxt=10001msec
Disk stats (read/write):
sdc: ios=136380/2, merge=0/1, ticks=7707/0, in_queue=7708, util=77.09%（4）随机写
[root@centos7 test]# fio -fimename=/dev/sdc1 -direct=1 -rw=randwrite -iodepth=1 -ioengine=psync -bs=4k -size=2G -numjobs=1 -runtime=10 -group_reporting -name=name
name: (g=0): rw=randwrite, bs=4K-4K/4K-4K/4K-4K, ioengine=psync, iodepth=1
fio-2.1.10
Starting 1 process
Jobs: 1 (f=1): [w] [100.0% done] [0KB/56419KB/0KB /s] [0/14.2K/0 iops] [eta 00m:00s]
name: (groupid=0, jobs=1): err= 0: pid=16046: Sun May 9 00:10:27 2021
write: io=568740KB, bw=56868KB/s, iops=14217, runt= 10001msec
clat (usec): min=54, max=896, avg=68.65, stdev=13.78
lat (usec): min=54, max=897, avg=68.85, stdev=13.78
clat percentiles (usec):
| 1.00th=[ 59], 5.00th=[ 60], 10.00th=[ 61], 20.00th=[ 62],
| 30.00th=[ 63], 40.00th=[ 64], 50.00th=[ 65], 60.00th=[ 67],
| 70.00th=[ 69], 80.00th=[ 73], 90.00th=[ 78], 95.00th=[ 85],
| 99.00th=[ 113], 99.50th=[ 129], 99.90th=[ 223], 99.95th=[ 290],
| 99.99th=[ 450]
bw (KB /s): min=54344, max=59800, per=100.00%, avg=56980.63, stdev=1192.52
lat (usec) : 100=97.66%, 250=2.27%, 500=0.06%, 750=0.01%, 1000=0.01%
cpu : usr=0.08%, sys=91.91%, ctx=41937, majf=0, minf=27
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 : total=r=0/w=142185/d=0, short=r=0/w=0/d=0
latency : target=0, window=0, percentile=100.00%, depth=1
Run status group 0 (all jobs):
WRITE: io=568740KB, aggrb=56868KB/s, minb=56868KB/s, maxb=56868KB/s, mint=10001msec, maxt=10001msec
Disk stats (read/write):
sdc: ios=0/141304, merge=0/1, ticks=0/9746, in_queue=9744, util=97.26%（5）混合顺序读写
[root@centos7 test]# fio -fimename=/dev/sdc1 -direct=1 -rw=rw -iodepth=1 -ioengine=psync -bs=4k -size=2G -numjobs=1 -runtime=10 -group_reporting -name=name
name: (g=0): rw=rw, bs=4K-4K/4K-4K/4K-4K, ioengine=psync, iodepth=1
fio-2.1.10
Starting 1 process
Jobs: 1 (f=1): [M] [100.0% done] [23032KB/23336KB/0KB /s] [5758/5834/0 iops] [eta 00m:00s]
name: (groupid=0, jobs=1): err= 0: pid=16102: Sun May 9 00:11:33 2021
read : io=300452KB, bw=30042KB/s, iops=7510, runt= 10001msec
clat (usec): min=41, max=741, avg=60.08, stdev=15.11
lat (usec): min=41, max=744, avg=60.22, stdev=15.11
clat percentiles (usec):
| 1.00th=[ 46], 5.00th=[ 49], 10.00th=[ 50], 20.00th=[ 51],
| 30.00th=[ 51], 40.00th=[ 52], 50.00th=[ 53], 60.00th=[ 55],
| 70.00th=[ 64], 80.00th=[ 73], 90.00th=[ 77], 95.00th=[ 81],
| 99.00th=[ 102], 99.50th=[ 122], 99.90th=[ 177], 99.95th=[ 211],
| 99.99th=[ 442]
bw (KB /s): min=22960, max=34376, per=100.00%, avg=30410.95, stdev=4527.95
write: io=300316KB, bw=30029KB/s, iops=7507, runt= 10001msec
clat (usec): min=53, max=994, avg=70.09, stdev=16.20
lat (usec): min=53, max=994, avg=70.29, stdev=16.21
clat percentiles (usec):
| 1.00th=[ 57], 5.00th=[ 58], 10.00th=[ 59], 20.00th=[ 59],
| 30.00th=[ 60], 40.00th=[ 61], 50.00th=[ 63], 60.00th=[ 66],
| 70.00th=[ 76], 80.00th=[ 85], 90.00th=[ 89], 95.00th=[ 93],
| 99.00th=[ 113], 99.50th=[ 135], 99.90th=[ 185], 99.95th=[ 223],
| 99.99th=[ 434]
bw (KB /s): min=23336, max=34048, per=100.00%, avg=30375.16, stdev=4390.51
lat (usec) : 50=2.54%, 100=95.58%, 250=1.85%, 500=0.03%, 750=0.01%
lat (usec) : 1000=0.01%
cpu : usr=0.11%, sys=81.47%, ctx=103856, majf=0, minf=29
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 : total=r=75113/w=75079/d=0, short=r=0/w=0/d=0
latency : target=0, window=0, percentile=100.00%, depth=1
Run status group 0 (all jobs):
READ: io=300452KB, aggrb=30042KB/s, minb=30042KB/s, maxb=30042KB/s, mint=10001msec, maxt=10001msec
WRITE: io=300316KB, aggrb=30028KB/s, minb=30028KB/s, maxb=30028KB/s, mint=10001msec, maxt=10001msec
Disk stats (read/write):
sdc: ios=74842/74787, merge=0/1, ticks=4097/4760, in_queue=8855, util=88.22%（6）混合随机读写
[root@centos7 test]# fio -fimename=/dev/sdc1 -direct=1 -rw=randrw -iodepth=1 -ioengine=psync -bs=4k -size=2G -numjobs=1 -runtime=10 -group_reporting -name=name
name: (g=0): rw=randrw, bs=4K-4K/4K-4K/4K-4K, ioengine=psync, iodepth=1
fio-2.1.10
Starting 1 process
Jobs: 1 (f=1): [m] [100.0% done] [23160KB/23648KB/0KB /s] [5790/5912/0 iops] [eta 00m:00s]
name: (groupid=0, jobs=1): err= 0: pid=16210: Sun May 9 00:13:45 2021
read : io=290024KB, bw=29000KB/s, iops=7249, runt= 10001msec
clat (usec): min=44, max=771, avg=62.03, stdev=14.93
lat (usec): min=44, max=771, avg=62.16, stdev=14.93
clat percentiles (usec):
| 1.00th=[ 48], 5.00th=[ 50], 10.00th=[ 51], 20.00th=[ 52],
| 30.00th=[ 53], 40.00th=[ 55], 50.00th=[ 57], 60.00th=[ 60],
| 70.00th=[ 66], 80.00th=[ 73], 90.00th=[ 78], 95.00th=[ 84],
| 99.00th=[ 102], 99.50th=[ 118], 99.90th=[ 179], 99.95th=[ 221],
| 99.99th=[ 470]
bw (KB /s): min=23384, max=32232, per=100.00%, avg=29312.00, stdev=3044.28
write: io=289732KB, bw=28970KB/s, iops=7242, runt= 10001msec
clat (usec): min=54, max=771, avg=72.58, stdev=14.81
lat (usec): min=54, max=771, avg=72.78, stdev=14.82
clat percentiles (usec):
| 1.00th=[ 59], 5.00th=[ 60], 10.00th=[ 61], 20.00th=[ 62],
| 30.00th=[ 63], 40.00th=[ 65], 50.00th=[ 67], 60.00th=[ 71],
| 70.00th=[ 78], 80.00th=[ 85], 90.00th=[ 90], 95.00th=[ 96],
| 99.00th=[ 114], 99.50th=[ 131], 99.90th=[ 187], 99.95th=[ 225],
| 99.99th=[ 298]
bw (KB /s): min=23704, max=32056, per=100.00%, avg=29257.26, stdev=2921.99
lat (usec) : 50=1.26%, 100=96.35%, 250=2.35%, 500=0.03%, 750=0.01%
lat (usec) : 1000=0.01%
cpu : usr=0.17%, sys=85.70%, ctx=81379, majf=0, minf=27
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 : total=r=72506/w=72433/d=0, short=r=0/w=0/d=0
latency : target=0, window=0, percentile=100.00%, depth=1
Run status group 0 (all jobs):
READ: io=290024KB, aggrb=28999KB/s, minb=28999KB/s, maxb=28999KB/s, mint=10001msec, maxt=10001msec
WRITE: io=289732KB, aggrb=28970KB/s, minb=28970KB/s, maxb=28970KB/s, mint=10001msec, maxt=10001msec
Disk stats (read/write):
sdc: ios=72006/71942, merge=0/1, ticks=4119/4861, in_queue=8976, util=89.73%5、输出结果解释说明
IOPS (英文：Input/Output Operations Per Second)，即每秒进行读写（I/O）操作的次数，多用于数据库、存储等场合，衡量随机访问的性能。
主要查看iops
iops ：磁盘的每秒读写次数，这个是随机读写考察的重点
bw ：磁盘的吞吐量，这个是顺序读写考察的重点，类似于下载速度
avg ：每个IO请求的平均相应时间
io ：总的输入输出量
runt ：总运行时间
msec ：毫秒
usec ：微秒
lat (msec)：延迟(毫秒)随机关注IOPS 因为随机读写的话，每次IO操作的寻址时间和旋转延时都不能忽略不计，而这两个时间的存在也就限制了IOPS的大小
而顺序读写关注bw 可以忽略不计寻址时间和旋转延时，主要花费在数据传输的时间上。
注意：尽量避免对有数据的磁盘或者分区做测试，谨慎操作，可能理解不够透彻的话参数使用错误会破坏已存在的数据