让CentOS32位支持大于4G内存

遇到一台CentOS 5.6的机器需要升级内存到6GB,结果发现系统居然是32位的，于是搜索能否让32位系统支持4G以上内存的方法。

如何让linux/Centos 32位支持8G内存?内核安装PAE支持大于4GB内存的方法。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：

[[email protected]]# free total used freeshared buffers cached Mem: 3881968 637928 3244040 0 111292 461680 -/+ buffers/cache: 64956 3817012 Swap: 4192924 0 4192924 [[email protected]]# 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 setto 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! [[email protected]]# free total used freeshared buffers cached Mem: 3881968 637928 3244040 0 111292 461680 -/+ buffers/cache: 64956 3817012 Swap: 4192924 0 4192924 [[email protected]]# 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 [[email protected]]# 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 forreboot Now! [[email protected]]# free total used freeshared buffers cached Mem: 8295488 215248 8080240 0 19460 142592 -/+ buffers/cache: 53196 8242292 Swap: 4192924 0 4192924

升级完成，可以支持大内存了。