The Kevin Appel

Powerpath and Redhat

admin — Fri, 14 May 2010 02:07:07 +0000

Do you know that Redhat and Novell handle their boot process completely different? Yes it’s true, Novell has modularized their boot process into individual files under /etc however Redhat 5 currently handles this in a linear process. Ok thanks now I feel smarter, but how does this affect me? Here’s the deal, third party vendors that need to be leveraged, have to insert their code into the boot process so their modules are loaded and their product is functional. On a typical Sles machine these files will be inserted into the boot.d structure; however on a Redhat system the code will be injected into rc.sysinit.

Now we get to the core, on Redhat machine who owns the /etc/rc.d/rc.sysinit file, yes you are correct, it is from initscripts. And this is important because? Well this is a rpm package that can and will be updated via content, therefore overriding any content that was previously stored. And then the multipath is broken …

Have no fear however, the solution is a quick fix. By restarting Powerpath (/etc/init.d/PowerPath start), it will re-inject itself into sysinit, which will provide the mechanism to survive a reboot and allow the modules to be loaded at default and re-enable your file systems depending upon the emc pseudo devices.

Restoring the Stage 1 Grub Loader in Linux

admin — Sun, 14 Mar 2010 13:54:41 +0000

Sometimes things go wrong when working with Linux, whether a side effect related to a process during patching or a mis-issued command can render your system unusable.

In this brief post, I will describe a process that can be used in the event you have blown away Grub from the MBR (Master Boot Record). This recovery takes a few minutes and in the event occurs to you, can save hours if your planned solution was rebuild and restore.

How do I know if this is possibly the issue that is affecting me? The Linux boot process involves a few stages, the focus here will be based on the Stage 1 loader which occurs when the MBR is pulled to determine what boot loader should be used to facilitate the Stage 2 process. A very common sympton that will occur when the Stage 1 loader is having issues is seeing only “GRUB ” when your system boots. This is a common indicator that the system is having problems locating the device map and allowing it to proceed to Stage 2 and continue with the boot process.

If this is the case that your system is experiencing, the process to restore is booting into rescue mode, mounting the file systems, and restoring the grub loader. The below steps assume your boot partition is the first primary partition on your system, your root file system is contained inside LVM, called rootvg, and your / is called rootlv, and your primary disk’s name is sda.

First is to boot into rescue mode, this is defined based on the Linux distribution but is usually a trivial task and utilizes the rescue prompts provided from the media. The next step is to mount your current disk in the rescue mode so it can be used for the repair.

mount /dev/rootvg/rootlv /mnt

mount /dev/sda1 /mnt/boot

grub-install –root-directory=/mnt /dev/sda1

umount /mnt/boot

umount /mnt

sync

reboot

The above commands will restore the grub loader and allow your system to move on after the Stage 1 loader, the above file systems and device names need to be adjusted given your setup

Check out the new Lemon Lime front page

admin — Sat, 13 Mar 2010 19:46:57 +0000

Just updated the home page for Lemon Lime, now in living colour.

http://www.lemonlimeagency.com

Hot off the press, new mnsav website

admin — Sat, 13 Mar 2010 19:59:23 +0000

M&S Associates debut of their highly demanded Audio and Video work, check it out

http://www.mnsav.com