Getting my server to boot from a Live-CD again

It's become one of my most said things when it comes to computers: "Why can't things simply work?"

Indeed, I always seem to stumble over things when working with comps that don't seem to function the way they should - or I as a user simply would expect them to. Yes, I'm a geek and I can work it out usually or find a workaround, but I often think "why the heck do I have to do this in the first place?"

Same today. I wanted to clone one of my old harddisks. Since it contained a Linux-installation, I figured I'd simply use the good old dd to copy the whole disk content. I wanted to use the new harddisk as a replacement for the old one, so it would come in handy to copy the MBR and the partition table aswell that way. I was even lucky: I found a disk with exactly the same amount of space and the same drive geometry as my old one. That's definitely not a given fact, but I was happy and it felt like a cheap and easy thing to do. Of course I can't do it while the Linux system itself uses the disk, so I planned to boot up whatever Live-system I have laying around while having the 2 harddisks connected and I'll be all set. I planned to use my good old external USB DVD-burner as a the boot-drive.

But for some strange reason, my system didn't want to boot the CD. Everyone that I tried stopped and the ISOLINUX loader showed me an "image checksum error". I've used the exact same CDs/DVDs before, so I knew it was no problem of the discs themselves. I figured it must be something with the way the BIOS tries to interpret and access the discs. But again, it was strange since I used the exact same optical drive to actually install the current system...

Well, after some trying around with different BIOS-settings - without success - I started to narrow it down. How to do that best? well, as usual: disconnect and turn off everything you don't really need, see if it works then, and then start reconnecting things one by one until it doesn't work again. And to my surprise, it turned out that the new harddrive was causing problems! I have no idea why, but as long as it was connected while the system was booting up, it messed up with the ISOLINUX loader of the Live-CDs somehow. So since it's a USB harddrive, I simply left it unplugged while booting and added it later when the system was up.

So again, I had to fumble around and try stuff and figure out what the problem was and look up message-boards and knowledge-bases online... people wonder why I know so much about these things. It's easy: because all that stuff has happened to me before!

Now after the copying is done and my system up again, I'll have to investigate a far more time-consuming problem: rare, occasional disconnects of one other USB-harddrive. Seems like a Linux-kernel thing or maybe a problem or incompatibility with the hardware - either of the drive or of the board-chipset.... the usual stuff, I'm off to consult more knowledge-bases online...