将 RHEL 5.4 升级为 CentOS 5.5

因为 RHEL 5.4 trial 到期不能 yum,一些安全 BUG 看着不能升级真的感到很蛋疼。于是尝试着将 RHEL 5.4 转换为 CentOS 5。首先当然是用 root 登录

yum clean all
mkdir ~/centos
cd ~/centos/
wget http://mirror.centos.org/centos/RPM-GPG-KEY-CentOS-5

wget http://mirror.centos.org/centos/5.5/os/i386/CentOS/centos-release-5-5.el5.centos.i386.rpm
wget http://mirror.centos.org/centos/5.5/os/i386/CentOS/centos-release-notes-5.5-0.i386.rpm
wget http://mirror.centos.org/centos/5.5/os/i386/CentOS/yum-3.2.22-26.el5.centos.noarch.rpm
wget http://mirror.centos.org/centos/5.5/os/i386/CentOS/yum-fastestmirror-1.1.16-14.el5.centos.1.noarch.rpm
wget http://mirror.centos.org/centos/5.5/os/i386/CentOS/yum-updatesd-0.9-2.el5.noarch.rpm
rpm –import RPM-GPG-KEY-CentOS-5
rpm -e –nodeps RedHat-release
rpm -e –nodeps yum-rhn-plugin
rpm -Uvh –force *.rpm
yum clean all
rpm –rebuilddb
yum update
重启一下,应该就是 CentOS 5.5 咯。

四步轻松升级CentOS内核

因为需要测试一些软件,需要2.6.30以上的内核,安装好CentOS 5.5,内核是2.6.18-194.el5.这次的升级还算比较顺利,具体的过程如下:

[root@localhost ~]# uname -r
2.6.18-194.el5
1.下载linux-2.6.30内核包到/usr/src目录
cd /usr/src
wget ftp://ftp.kernel.org/pub/linux/kernel/v2.6/linux-2.6.30.tar.gz
tar -xzvf linux-2.6.30.tar.bz2 -C /usr/src
cd linux-2.6.30
make mrproper 清除环境变量,即清除配置文件
make menuconfig 在菜单模式下选择需要编译的内核模块:
networking support—>networking options—>network packet filtering framework(netfilter)
(1).core netfilter configuration
A 勾中”Netfilter connection tracking support” -m state相关模块是依赖它的,不选则没有。
B 将netbios name service protocal support(new) 编译成模块,不然后面升级iptables后启动时会出错
C 勾中“Netfilter Xtables support (required for ip_tables)”
(2).IP: Netfilter Configuration
A 将 “IPv4 connection tracking support (require for NAT)” 编译成模块。
B 勾中IP tables support (required for filtering/masq/NAT) 。
C 将 “Full NAT” 下的 “MASQUERADE target support” 和 “REDIRECT target support” 编译成模块
(3).其它模块可以根据自己的需要进行选择,若不懂可以参考内核配置手册.
make clean 确保所有东西均保持最新状态.
make bzImage 生成内核文件
make modules 编译模块
make modules_install 安装模块
make install 安装
mkinitrd /boot/initrd_2.6.30.img 2.6.30 根据内核版本和指定参数生成映像文件
cp arch/x86/boot/bzImage /boot/vmlinuz-2.6.30
cp /usr/src/linux-2.6.30/System.map /boot/System.map-2.6.30

2.在/etc/grub.conf添加如下2.6.30的信息,并把default=1改为default=0
[root@localhost ~]# cat /etc/grub.conf
# grub.conf generated by anaconda
#
# Note that you do not have to rerun grub after making changes to this file
# NOTICE: You have a /boot partition. This means that
# all kernel and initrd paths are relative to /boot/, eg.
# root (hd0,0)
# kernel /vmlinuz-version ro root=/dev/VolGroup00/LogVol00
# initrd /initrd-version.img
#boot=/dev/sda
default=0
timeout=5
splashimage=(hd0,0)/grub/splash.xpm.gz
hiddenmenu
title CentOS (2.6.18-194.el5)
root (hd0,0)
kernel /vmlinuz-2.6.18-194.el5 ro root=/dev/VolGroup00/LogVol00 rhgb quiet
initrd /initrd-2.6.18-194.el5.img
title CentOS (2.6.30)
root (hd0,0)
kernel /vmlinuz-2.6.30 ro root=/dev/VolGroup00/LogVol00 rhgb quiet
initrd /initrd-2.6.30.img

3.此步若没有操作,重启会报错”insmod: error inserting ‘/lib/dm-region-hash.ko’: –1 File exits”,原因是重复了,根据网上查到的资料,2.6.x自编译内核会有这个小bug,我测试过不修改直接重启,虽然有报错,但仍然可以进入系统的.
[root@localhost]cp /boot/initrd-2.6.30.img /tmp
[root@localhost]cd /tmp/
[root@localhost tmp]mkdir newinitrd
[root@localhost tmp]cd newinitrd/
[root@localhost newinitrd]zcat ../initrd-2.6.30.img |cpio -i
[root@localhost newinitrd]vi init 删掉重复的如下两行:
echo “Loading dm-region-hash.ko module”
insmod /lib/dm-region-hash.ko
[root@localhost newinitrd]# find .|cpio -c -o > ../initrd
14765 blocks
[root@localhost newinitrd]# cd ..
[root@localhost tmp]# gzip -9 < initrd > initrd-2.6.30.img
[root@localhost tmp]# ls
gconfd-root initrd initrd-2.6.30.img mapping-root newinitrd scim-panel-socket:0-root
[root@localhost tmp]# mv /boot/initrd-2.6.30.img /home/
[root@localhost tmp]# cp initrd-2.6.30.img /boot/
[root@localhost tmp]#reboot

4.重启成功后,再看看内核,是2.6.30,ok了。
[root@localhost ~]# uname -r
2.6.30