Ubuntu on a Dell: Episode 3: Revenge of the RAID
The saga continues! Well, after looking into software RAID on Linux everything pointed to me having to install the system all over again. I tried to find an easy way of using the existing partitions (such as by setting up the secondary disk as a RAID device, copying the partition data from the primary disk, then formatting it, adding it to the RAID device and finally rebuilding the RAID) but that was going to be a lot of hassle with no guarantee of success. So I decided to just bite the bullet and reinstall with one of the Ubuntu alternate install discs.
It turns out that installing a software RAID with the alternate discs is a lot easier than I would have guessed. I did have
this guide to follow, which made it easier as well. I just had to partition the disks, set them to use "physical volume for RAID" instead of the normal file system and then ask the partitioner to start setting up RAID. It then goes through setting up each multi-disk device (md) and the options are well explained and fairly self-explanatory anyway. Someone that I liked is that, with software RAID, you can set up one pair of partitions to be RAID1, another RAID0, etc. Very flexible.
So, overall, this install method seemed to have worked for me. At the very least it's a lot easier than I feared.
The rest of the install went smoothly. The ncurses-based installer is pretty similar to the graphical (GTK+?) installer in terms of what options it has and the questions it asks. Interesting to note is that the alternate install actually gives you the option to set up available X resolutions … and the list includes widescreen resolutions! I'd still want to change the
xorg.conf file to set the correct vertical and horizontal refresh rates for the monitor I'm using but it's nice to start off with the correct resolution. It does make you wonder why the graphical installer couldn't do something similar or just damn well support widescreen monitors. Something for the next version of Ubuntu perhaps.
Having completed the install, I rebooted to find … nothing. The system refused to boot and dropped me into an busybox prompt which didn't do anything. I rebooted again and the system booted, although it took ages and told me that there were no device set up in the mdadm config file. Strange. Once I'd gotten to the desktop (in glorious 1680×1050) the system was reporting that the md devices were being used so I guess everything worked fine. Very strange. If I had to guess I'd say that the relevant partitions and RAID devices (especially the partition with /boot) just had to be initialised and loaded properly with data. Or something. Checking the
/proc/mdstat file showed that the /home partition was in the process of being resynced so this reinforces my guess.
Another reboot and I was being left with a non-booting system again. It's still saying that there are no devices found in the mdadm config file but also that the md0 devices is busy. Another reboot didn't fix the issue. Feeling frustrated I left the computer for a while and started looking up information on the problem on the Ubuntu forums. Turns out it's not that uncommon an issue and seems to stem from a race condition between udev and mdadm, along with a problem where mdadm doesn't properly shut down, or something like that. I didn't find any compelling information that would fix my problem so I booted again and things went alright. The computer booted but it still took ages to even get to GRUB.
Sigh. The system seems to work now (I rebooted a few times to check) and I'm going to hope for the best. My next task will be to simulate a non-functioning disk and check that the RAID1 I've spent all this effort to get to work actually does its job! Otherwise I may be going to look up how to get the chipset's RAID drivers installed.
Let's see if this saga concludes soon! I hope to get some concrete results out of all this that I can pass on to others.