I spent this past weekend hacking away at my Media Box, which serves as my personal free PVR. I wanted to get Ubuntu on it with LVM so I could use all four of my hard drives as one for MythTV. I borrowed one of Vlad’s Ubuntu CD’s (mine haven’t arrived yet and I couldn’t find the one I burnt) and got the installer running. During the partitioning section of the install, I set everything up for an LVM volume group and thought I had everything working. Apparently I didn’t. Silly me for not having a clue how LVM works (always read the directions, kids).
Anyway, my installation was b0rked so I figured I’d just reboot and start from scratch. No. My LVM data was still present every time I tried to install Ubuntu. I would try to remove the volume groups and it would fail, reporting the drives were still in use. I was getting manifest errors up the wazoo. So I thought, ‘OK, I just need to wipe the drives with something else and I’ll be fine.’ So I tried booting off an XP CD into rescue mode and formatting the drives there. No dice. I downloaded a few CD-based disk formatting tools that said they cleared things out but apparently they didn’t. Google searches were returning a whole bunch of information about how to remove volume groups, but nothing about how to forcefully wipe LVM volumes. Funny… most people that use LVM and software RAID are concerned about keeping their data safe. Whatever.
Finally, I came across this forum post, which has the necesarry command. In retrospect it makes sense - just write zeroes to the first part of the disk. But I would have never figured it out. For posterity, here’s the command you need to run on a device to remove all previous LVM info:
dd if=/dev/zero of=/dev/sda bs=1k count=10
Then of course, I had to figure out how the Ubuntu installer was mounting all my drives… but that’s another story. And by the way… after all of this, MythTV just wasn’t liking my remote, and I was suffering PVR withdrawal pretty bad, so I’m back to MCE2005. Looks like I’ll have to keep fast-forwarding through the commercials manually. Such is life.