iotop是一个用来监视磁盘I/O使用状况的 top 类工具，可监测到哪一个程序使用的磁盘IO的信息，磁盘io异常时可以用来排查问题。
直接输入iotop时输出,可以看到系统磁盘io负载不高：
Total DISK READ: 0.00 B/s | Total DISK WRITE: 393.90 K/s
TID PRIO USER DISK READ DISK WRITE SWAPIN IO> COMMAND
1143 be/3 root 0.00 B/s 30.59 K/s 0.00 % 5.14 % [jbd2/sda3-8]
12122 be/4 root 0.00 B/s 11.47 K/s 0.00 % 0.00 % syslog-ng -p /var/run/syslog-ng.pid
2048 be/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % sh -c echo "[`date +"%F %T"`] `/usr/~ /tmp/crontab_uploadSourceAsBs2.log &
1 be/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % init
2 be/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [kthreadd]
3 be/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [ksoftirqd/0]
6 rt/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [migration/0]
7 rt/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [watchdog/0]
8 rt/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [migration/1]
10 be/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [ksoftirqd/1]
26635 be/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % ./devops_channel_d --c channel.conf --d disable
12 rt/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [watchdog/1]
13 rt/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [migration/2]
14 be/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [kworker/2:0]
15 be/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [ksoftirqd/2]
16 rt/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [watchdog/2]
17 rt/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [migration/3]
19 be/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [ksoftirqd/3]
20 rt/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [watchdog/3]
21 rt/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [migration/4]
2070 be/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % php /data/webapps/sy.admin.duowan.co~tected/bin/game/uploadSourceAsBs2.php
23 be/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [ksoftirqd/4]
24 rt/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [watchdog/4]
25 rt/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [migration/5]
27 be/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [ksoftirqd/5]
28 rt/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [watchdog/5]
29 rt/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [migration/6]
31 be/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [ksoftirqd/6]
32 rt/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [watchdog/6]
33 rt/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [migration/7]
35 be/4 root 0.00 B/s 0.00 B/s 0.00 % 0.00 % [ksoftirqd/7]
hejianping@ubuntu:~$ 0.00 B/s 0.00 B/s 0.00 % 0.00 % [watchdog/7]
常用参数：
-n：显示输出次数 -o：只显示有io输出的进程 -b：阻止动态显示
最常用使用的组合：
iotop -bon5
hejianping@ubuntu:~$ sudo iotop -bon5 Total DISK READ: 0.00 B/s | Total DISK WRITE: 0.00 B/s TID PRIO USER DISK READ DISK WRITE SWAPIN IO COMMAND 5373 be/4 root 0.00 B/s 70.52 K/s 0.00 % 0.00 % bash /data/services/rsync-3.0.7.4/admin/report.sh Total DISK READ: 0.00 B/s | Total DISK WRITE: 287.33 K/s TID PRIO USER DISK READ DISK WRITE SWAPIN IO COMMAND 16716 be/4 root 0.00 B/s 3.83 K/s 0.00 % 0.00 % ./yyms_agent_d 12122 be/4 root 0.00 B/s 7.66 K/s 0.00 % 0.00 % syslog-ng -p /var/run/syslog-ng.pid Total DISK READ: 0.00 B/s | Total DISK WRITE: 0.00 B/s TID PRIO USER DISK READ DISK WRITE SWAPIN IO COMMAND 23842 be/4 www-data 0.00 B/s 3.83 K/s 0.00 % 0.00 % nginx: worker process Total DISK READ: 122.51 K/s | Total DISK WRITE: 520.68 K/s TID PRIO USER DISK READ DISK WRITE SWAPIN IO COMMAND 1143 be/3 root 0.00 B/s 248.86 K/s 0.00 % 4.11 % [jbd2/sda3-8] 497 be/3 root 0.00 B/s 126.34 K/s 0.00 % 3.42 % [jbd2/sda1-8] 23842 be/4 www-data 0.00 B/s 7.66 K/s 0.00 % 0.00 % nginx: worker process 23848 be/4 www-data 122.51 K/s 0.00 B/s 0.00 % 0.00 % nginx: worker process Total DISK READ: 0.00 B/s | Total DISK WRITE: 0.00 B/s TID PRIO USER DISK READ DISK WRITE SWAPIN IO COMMAND 19119 be/4 root 0.00 B/s 3.83 K/s 0.00 % 0.00 % ./yyms_agent_d 843 be/4 root 0.00 B/s 7.65 K/s 0.00 % 0.00 % ./yyms_agent_d 23836 be/4 www-data 0.00 B/s 3.83 K/s 0.00 % 0.00 % nginx: worker process hejianping@ubuntu:~$
可以看出，该服务器上面并没有占用磁盘io较高的业务。