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一、检查系统的状态
通过操作系统的一些工具检查系统的状态，比如CPU、内存、交换、磁盘的利用率，根据经验或与系统正常时的状态相比对，有时系统表面上看起来看空闲，这也可能不是一个正常的状态，因为cpu可能正等待IO的完成。除此之外，还应观注那些占用系统资源(cpu、内存)的进程。
1.使用sar来检查操作系统是否存在IO问题
#sar-u210― 即每隔2秒检察一次，共执行20次。
结果示例：
注：在redhat下，%system就是所谓的%wio。
Linux2.4.21-20.ELsmp (YY075)05/19/2005
10:36:07AMCPU%user%nice%system%idle
10:36:09AMall0.000.000.1399.87
10:36:11AMall0.000.000.00100.00
10:36:13AMall0.250.000.2599.49
10:36:15AMall0.130.000.1399.75
10:36:17AMall0.000.000.00100.00
其中：
%usr指的是用户进程使用的cpu资源的百分比;
%sys指的是系统资源使用cpu资源的百分比;
%wio指的是等待io完成的百分比，这是值得观注的一项;
%idle即空闲的百分比。
如果wio列的值很大，如在35%以上，说明系统的IO存在瓶颈，CPU花费了很大的时间去等待I/O的完成。Idle很小说明系统CPU很忙。像以上的示例，可以看到wio平均值为11，说明I/O没什么特别的问题，而idle值为零，说明cpu已经满负荷运行了。
2.使用vmstat监控内存 cpu资源
[root@mysql1 ~]# vmstat
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