如何让linux/Centos 32位支持大于4G内存

資料來源：http://carllai.blog.51cto.com/1664997/1225762



linux/Centos 32bit OS 默认不支持4G以上内存的，安装一个kernel-PAE补丁就可以解决了，操作前最好对虚拟机做一个快照备份，以防出现意外时可以恢复到正常状态。

下面是几个步骤：

[root@www.ctohome.com]# free

total used free shared buffers cached

Mem: 3881968 637928 3244040 0 111292 461680

-/+ buffers/cache: 64956 3817012

Swap: 4192924 0 4192924

[root@www.ctohome.com]# yum install kernel-PAE

Loaded plugins: fastestmirror

Loading mirror speeds from cached hostfile

centos-burstnet | 1.1 kB 00:00

updates-burstnet | 1.9 kB 00:00

Setting up Install Process

Resolving Dependencies

--> Running transaction check

---> Package kernel-PAE.i686 0:2.6.18-194.32.1.el5 set to be installed

--> Finished Dependency Resolution

Dependencies Resolved

==========================================================

Package Arch Version Repository Size

==========================================================

Installing:

kernel-PAE i686 2.6.18-194.32.1.el5 updates-burstnet 17 M

Transaction Summary

==========================================================

Install 1 Package(s)

Upgrade 0 Package(s)

Total download size: 17 M

Is this ok [y/N]: y

Downloading Packages:

kernel-PAE-2.6.18-194.32.1.el5.i686.rpm | 17 MB 00:01

Running rpm_check_debug

Running Transaction Test

Finished Transaction Test

Transaction Test Succeeded

Running Transaction

Installing : kernel-PAE 1/1

Installed:

kernel-PAE.i686 0:2.6.18-194.32.1.el5

Complete!

[root@www.ctohome.com]# free

total used free shared buffers cached

Mem: 3881968 637928 3244040 0 111292 461680

-/+ buffers/cache: 64956 3817012

Swap: 4192924 0 4192924

[root@www.ctohome.com]# vi /boot/grub/grub.conf

default=0 #（把default=1改成default=0）

timeout=5

splashimage=(hd0,0)/grub/splash.xpm.gz

hiddenmenu

title CentOS (2.6.18-194.32.1.el5PAE) #（有这行PAE的就表示安装pae内核成功）

root (hd0,0)

kernel /vmlinuz-2.6.18-194.32.1.el5PAE ro root=LABEL=/

initrd /initrd-2.6.18-194.32.1.el5PAE.img

title CentOS (2.6.18-194.32.1.el5)

root (hd0,0)

kernel /vmlinuz-2.6.18-194.32.1.el5 ro root=LABEL=/

initrd /initrd-2.6.18-194.32.1.el5.img

title CentOS (2.6.18-194.el5)

root (hd0,0)

kernel /vmlinuz-2.6.18-194.el5 ro root=LABEL=/

initrd /initrd-2.6.18-194.el5.img

[root@www.ctohome.com]# reboot （这里重启服务器，祈祷吧，有时候主板或网卡不支持，那么就只能联系机房了）

Broadcast message from root (pts/0) (Thu May 19 18:52:34 2011):

The system is going down for reboot NOW!

[root@www.ctohome.com]# free

total used free shared buffers cached

Mem: 8295488 215248 8080240 0 19460 142592

-/+ buffers/cache: 53196 8242292

Swap: 4192924 0 4192924