Tuesday, June 26, 2007

Odds and Ends

It's been 16 days since my last post, and there are many good reasons for that.

We've been chugging along, installing and testing, testing and reinstalling. Lots and lots of work to do. I've been putting in insane hours trying to get everything ready for the main components to arrive. Here are some neat details. 1st, a picture of knoppix booting on one of the X4600s.
Each penguin in that picture represents a CPU. In 3 months, you would see that boot with 16 penguins! Those would each represent 1 of the 4 cores in the new AMD 4core barcelona chip.

Next, I managed to figure out the way that Thumpers, or X4500's, boot. Grub on an X4500 is a very weird, fickle thing. You have to relax your brain and accept that it will not act the way you think it should.

When you are installing Rocks on a thumper, it can only see the first 24 drives, only one of which is bootable. It is very unfortunate that Sun decided to put the two bootable drives on the same scsi controller, since if you lose the controller, you can't boot. But whatever.

Here's how to get a thumper to boot with grub in linux. Install to /dev/sdy - while installing, the OS, via anaconda, sees the bootable disk as sdy - the 24th disk. At the end, you want to install grub to this disk (a quick synopsis of this is, in grub: device (hd1) /dev/sdy;root (hd1,0); setup (hd1);).

Once you have marked the drive with the grub magic, you now need to set up grub.conf to point to, get this, hd0. Yes, I know you set grub up on what you defined as hd1, but just accept this and move on.

While the machine is booting, the BIOS of the X4500 only present grub with two disks - disk 0 and disk 1. So in grub.conf, you need to point to 0, like this: root (hd0,0). Then, tell it where you installed root (like /dev/sdy1), so that once grub loads, it can find the kernel, etc. That is where I got hung up - I kept thinking grub would see what I defined as hd1, but it couldn't see it - it could only see hd0.

I know I'm not really explaining it well, but that's all that you need to do.

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