RHEL5支持大内存

安装 RHEL 5 ，硬件为 4G 内存，安装完成后显示为 3.2G
原因，没有安装 kernel-PAE-2.6.18-8.el5.i686.rpm 软件包。

RHEL 5 的文档中关于内核的说明：
Red Hat Enterprise Linux contains the following kernel packages
kernel :Contains the kernel for multi-processor systems.For x86 system,only the first 4GB of RAM is used.As such,x86systems with over 4GBof RAM should use the kernel-PAE.
kernel-devel :Contains the kernel headers and makefiles sufficient to bulid modules against the kernel package.
kernel-PAE (only for i686systems):This package offers the following key configuration options (in addition to the options already enabled for the kernel package)
        1.Support for over 4GB of RAM (up to 64GB for the x86)
        2.PAE(Physical Address Extension)or 3-level paging on x86 processors that support PAE
        3.4GB/4GB split:4GB of virtual address space for the kernel an almost 4GB for each userprocess on x86systtems
另外还有以下内核： kernel-PAE-devel,kernel-doc,kernel-headers,kernel-xen,kernel-xen-devel.


解决：
主要需要 2 个方面设置
1.bios: 在 bios 里开启对大内存的设置
2. 安装支持大内存的 kernel

安装 kernel-PAE-2.6.18-8.el5.i686.rpm
rpm -ivh kernel-PAE-2.6.18-8.el5.i686.rpm
安装完后，
vi /etc/grub.conf

如果看到如下代码 代表 PAE 内核已经安装好了
title Red Hat Enterprise Linux Server (2.6.18-8.el5PAE)
root (hd0,0)
kernel /vmlinuz-2.6.18-8.el5PAE ro root=LABEL=/ rhgb quiet
initrd /initrd-2.6.18-8.el5PAE.img
修改启动顺序，将 default=1 改为 default=0 即可

评论

1 楼 yangzb 2010-10-08  

RHEL / CentOS Support 4GB or more RAM ( memory )

by Vivek Gite · 21 comments

If you have 4 GB or more RAM use the Linux kernel compiled for PAE capable machines. Your machine may not show up total 4GB ram. All you have to do is install PAE kernel package.

This package includes a version of the Linux kernel with support for up to 64GB of high memory. It requires a CPU with Physical Address Extensions (PAE).
The non-PAE kernel can only address up to 4GB of memory. Install the kernel-PAE package if your machine has more than 4GB of memory (>=4GB).
How Do I Install PAE kernel?

To install PAE kernel, use yum command:
# yum install kernel-PAE
Output:

Loading "installonlyn" plugin
Setting up Install Process
Setting up repositories
Reading repository metadata in from local files
Parsing package install arguments
Resolving Dependencies
--> Populating transaction set with selected packages. Please wait.
---> Downloading header for kernel-PAE to pack into transaction set.
kernel-PAE-2.6.18-8.1.15. 100% |=========================| 207 kB    00:00
---> Package kernel-PAE.i686 0:2.6.18-8.1.15.el5 set to be installed
--> Running transaction check

Dependencies Resolved

=============================================================================
Package                 Arch       Version          Repository        Size
=============================================================================
Installing:
kernel-PAE              i686       2.6.18-8.1.15.el5  updates            12 M

Transaction Summary
=============================================================================
Install      1 Package(s)
Update       0 Package(s)
Remove       0 Package(s)        

Total download size: 12 M
Is this ok [y/N]: y
Downloading Packages:
(1/1): kernel-PAE-2.6.18- 100% |=========================|  12 MB    00:12
Running Transaction Test
Finished Transaction Test
Transaction Test Succeeded
Running Transaction
  Installing: kernel-PAE                   ######################### [1/1]

Installed: kernel-PAE.i686 0:2.6.18-8.1.15.el5
Complete!

Just reboot the server and make sure you boot with PAE kernel i.e. 2.6.18-8.1.15.el5PAE:
# reboot