centos 6 kernel update messes up grub

seccentral · 11-17-2014, 04:49 AM

so here's how a kernel update changed the /etc/grub.conf

Code:

default=0
timeout=5

        title CentOS (2.6.32-431.29.2.el6.x86_64)
        kernel /boot/vmlinuz-2.6.32-431.29.2.el6.x86_64 root=/dev/md2  ro crashkernel=auto SYSFONT=latarcyrheb-sun16 LANG=en_US.UTF-
8 KEYTABLE=us
        root (hd0,1)
        initrd /boot/initramfs-2.6.32-431.29.2.el6.x86_64.img
        title CentOS (2.6.32-431.23.3.el6.x86_64)
        kernel /boot/vmlinuz-2.6.32-431.23.3.el6.x86_64 root=/dev/md2  ro crashkernel=auto SYSFONT=latarcyrheb-sun16 LANG=en_US.UTF-
8 KEYTABLE=us
        root (hd0,1)
        initrd /boot/initramfs-2.6.32-431.23.3.el6.x86_64.img
        title linux centos6_64
        kernel /boot/vmlinuz-2.6.32-431.20.3.el6.x86_64 root=/dev/md2  ro
        root (hd0,1)
        initrd /boot/initrd-2.6.32-431.20.3.el6.x86_64.img

now i'm seeing this as i'm about to do a yum update and the system has a 120+ days uptime and the newest kernel isnt even installed: 2.6.32-504.1.3.el6

I'm afraid of doing a yum update. is there any way of -resetting- *safely* the kernel rpm ? i've messed up a box really bad by doing an update from 6.5 to 6.6 and had the old kernels removed prior to updating so i ended up with an unbootable no-failsafe-kernel box.

rknichols · 11-17-2014, 09:10 AM

Please edit your post and change the [QUOTE] ... [/QUOTE] tags to [CODE] ... [/CODE] tags so that formatting is preserved. What is it that you feel is wrong with that grub.conf file? It looks quite similar to mine. If you are not currently running the first listed kernel (2.6.32-431.29.2.el6.x86_64), you should reboot and verify that your system still runs properly, as that will be the first fallback kernel after you upgrade.

If you want to keep more of the old kernels available, edit /etc/yum.conf and change "installonly_limit=3" to a larger number.

seccentral · 11-17-2014, 09:21 AM

thanks for the yum.conf tip. sometimes when updating i get a file not found error or a root not found and thats fortunate when the system is close, if it's remote and i don't have kvm it's a shot in the dark

rknichols · 11-17-2014, 01:38 PM

You might also want to edit /etc/sysconfig/kernel and set "UPDATEDEFAULT=no" so that the newly installed kernel will not become the boot default until you've had a chance to see if the installation went OK. You can later edit grub.conf and set "default=0" to make the top stanza (which should be your newly installed kernel) the default.