flyinweb's blog

linux系统上可以使用（centos 2.6.18-144开始支持），dstat版本至少是：dstat-0.6.7-1.rf.noarch.rpm
安装
wget -c http://linux.web.psi.ch/dist/scientific/5/gfa/all/dstat-0.6.7-1.rf.noarch.rpm
rpm -Uvh dstat-0.6.7-1.rf.noarch.rpm

使用
# dstat -M topio -d -M topbio

Newer Linux kernels have per-process I/O accounting and you can use the iotop tool to find out what’s performing I/O, but in many cases I’m trying to find the source of an I/O problem in an older kernel. I found sort of a hack-ish way to do that today, while trying to figure out why a system was basically unresponsive.

I found a post on Stack Overflow that showed a way you can get per process I/O statistics from the kernel even in older kernels. I adapted this to my needs, and wrote a little script.

Mark Wong’s entry titled “Following up a couple questions from the presentation at PSU on January 8, 2009” just caught my eye:

What is ‘iopp’?

It’s a custom tool to go through the Linux process table to get i/o statistics per process. It is open source and can be downloaded from:

http://git.postgresql.org/?p=~markwkm/iopp.git;a=summary

Following are few situations where you may be interested in performing a filesystem benchmarking.

=> Deploying a new application that is very read and write intensive.
=> Purchased a new storage system and would like to measure the performance.
=> Changing the RAID level and would like to measure the performance of the new RAID.
=> Changing the storage parameters and would like to know the performance impact of this change

This article gives you a jumpstart on performing benchmark on filesystem using iozone a free Filesystem Benchmark utility.

系统启动顺序：

加载BIOS的硬件信息
└ 读取MBR的Boot Loader信息 stage1,stage2,grub.conf
└ Boot Loader加载内核 vminux,initrd
└ 内核执行init程序并取得inittab中运行信息
├ init执行/etc/rc.d/rc.sysinit
└ /etc/fstab加载分区等
├ init执行/etc/rc.d/rc
├ 启动对应运行级别的守护进程
└ 最后执行S99local,即/etc/rc.d/rc.local
└ init启动了mingetty，打开了终端供用户登录系统
└ 执行/bin/login程序
└ 成功登陆之后启动shell控制主机
└ shell配置脚本
├ /etc/profile --->/etc/profile.d/*.sh
└ ~user/.bash_profile
└ ~user/.bashrc
└ /etc/bashrc

在系统维护的过程中，随时可能有需要查看 CPU 使用率，并根据相应信息分析系统状况的需要。在 CentOS 中，可以通过 top 命令来查看 CPU 使用状况。运行 top 命令后，CPU 使用状态会以全屏的方式显示，并且会处在对话的模式 -- 用基于 top 的命令，可以控制显示方式等等。退出 top 的命令为 q （在 top 运行中敲 q 键一次）。