Posts Tagged ‘linux’

Linux Upgrades – Installation from a software raid

Wednesday, November 8th, 2006

I recently had to upgrade a few machines with a newer version of Linux. Unfortunately, the CD-ROM drives in these machines were not functioning, so I decided to upgrade the system via a hard drive install. Hard drive installs are pretty simple and are part of the standard distro for Redhat. However, the machines I had to upgrade were all set up with software raid 1.

My initial thought was to merely put in the raid location where the install media was located. However, the installation program does not allow this and actually presents a list of acceptable locations.

So from here, I decided to choose one of the 2 raid drives and use that instead. The system graciously accepted this and launched the GUI installer to complete the process. All went smoothly until I reached the final step in the wizard, the actual install. At this point the installer crashed with a Python error. Upon inspection of the error, it appeared that the drive I was trying to use for the installation media was not available. Closer inspection revealed the truth, mdadm started up and activated all of the raid partitions on the system, making the partition I needed unavailable.

So what do I do now? I re-ran the installation and deleted the raid partition, being careful to leave the physical partitions in-tact. Again, the installer crashed at the same step. It seems that the installer scanned the entire hard drive for raid partitions whether they had valid mount points or not.

I finally solved the problem through a crude hack during the setup phase of the installation. I made sure to delete the raid partition once again, leaving the physical drives in-tact. I stepped through the entire process but stopped just before the final install step. At this point, I switched to the CLI console via Ctrl-Shift-F2. I created a small bash script that looked something like this :

#!/bin/bash

mdadm –stop /dev/md3

exec /bin/bash ./myscript.bash

I ran this script and switched back to the installer via Ctrl-F6. I proceeded with the installation and the installer happily installed the OS onto the drives. Once completed, I switched back to the CLI console, edited the new /etc/fstab file and added a mount point for the raid drive I used, and rebooted. The system came up without any issues and ran normally.

Just thought I’d share this with the rest of you, should you run into the same situation. It took me a while to figure out how to make the system do what I wanted. Just be sure that your install media is on a drive that the installer will NOT need to write files to.