Remote kernel upgrade

If for some/many reasons after a kernel upgrade, the system does not reboot. Some hosting control panels can reboot the server into rescue mode. In this mode, you can edit the lilo.conf to go back to the previous working kernel. Make sure you backup the file first.

<br /> # check for available partitions<br /> fdisk -l</p> <p># mount partitions to fix lilo.cnf<br /> mount -t ext3 /dev/sda3 /mnt<br /> mount -t ext3 /dev/sda1 /mnt/boot<br /> chroot /mnt</p> <p># edit the file to boot to the previous kernel<br /> # and run lilo to activate the boot sector on harddrive<br /> # should not see any fatal error<br /> vi /etc/lilo.conf<br /> lilo -v -v<br />

Also, if you use “yum update” to upgrade the kernel, the default kernel might have too many extra/redundant modules that might cause the system hang while booting up. If it is the case, use a modified kernel (compile your own) with some minimal modules enabled (can see the modules in /lib/modules/2.6.17.5, change the version if needed).

<br /> lba32<br /> boot=/dev/sda<br /> delay=30<br /> vga=normal<br /> map=/boot/map<br /> default=2.6.17.5</p> <p>image=/boot/vmlinuz-2.6.17.5<br /> label=2.6.17.5<br /> read-only<br /> root=/dev/sda3<br />

The files in /boot
<br /> [root@s77 boot]# ll<br /> total 8444<br /> -rw-r–r– 1 root root 512 Sep 8 2005 boot.0300<br /> -rw-r–r– 1 root root 512 May 30 02:13 boot.0800<br /> -rw-r–r– 1 root root 5824 Jun 15 2004 boot.b<br /> -rw-r–r– 1 root root 612 Jun 15 2004 chain.b<br /> -rw-r–r– 1 root root 65917 Jul 11 22:52 config-2.6.17-1.2142_FC4<br /> -rw-r–r– 1 root root 1097128 Aug 14 21:27 initrd-2.6.17-1.2142_FC4.img<br /> drwx—— 2 root root 12288 Sep 8 2005 lost+found<br /> -rw——- 1 root root 23040 Aug 15 12:27 map<br /> -rw-r–r– 1 root root 640 Jun 15 2004 os2_d.b<br /> -rw-r–r– 1 root root 773898 Sep 8 2005 System.map-2.6.12.4<br /> -rw-r–r– 1 root root 832577 Jul 11 22:52 System.map-2.6.17-1.2142_FC4<br /> -rw-r–r– 1 root root 803128 Jul 15 14:18 System.map-2.6.17.5<br /> -rw-r–r– 1 root root 1238936 Sep 8 2005 vmlinuz-2.6.12.4<br /> -rw-r–r– 1 root root 1803676 Jul 11 22:52 vmlinuz-2.6.17-1.2142_FC4<br /> -rw-r–r– 1 root root 1934981 Jul 15 14:17 vmlinuz-2.6.17.5<br />