mounts wrong partition on boot

Bug #133152 reported by Paul Perkins on 2007-08-17
10
This bug affects 1 person
Affects Status Importance Assigned to Milestone
Ubuntu
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Bug Description

Kubuntu 7.04 (upgraded from 6.10) confuses partitions on different disks.

Machine is configured to dual boot with XP. Normally, when I boot Kubuntu, the XP partition is mounted on /media/xp (I think I assigned that pathname during the initial install). But, some time ago I made a backup copy of the XP partition onto a USB disk drive (using gparted). Recently I happened to boot Kubuntu with the USB disk drive powered on and plugged in, and the backup copy of the XP partition on the USB disk was mounted in place of the original XP partition on the computer's main (SATA) disk. Very confusing until I looked carefully at the output of "mount".

Brian Murray (brian-murray) wrote :

Thank you for taking the time to report this bug and helping to make Ubuntu better. You reported this bug a while ago and there hasn't been any activity in recently. We were wondering if this is still an issue for you? Thanks in advance.

EldestHanson (p-a-hanson) wrote :

This sounds very similar to my situation, and if so, the XP part of it is not the issue. It could instead be confusion between two bootable filesystems when they are too similar. That is, it sometimes picks a backup drive image if you have one connected.

I have two nearly identical IDE drives in my system. My boot drive is hda and currently holds Gutsy, while hdb is a bit-for-bit backup from some time ago, currently holding a not-quite-functional version of Dapper.

What seem to happen is the BIOS identifies hda as the first master, and boots to hda1. But when the boot scripts remount / for rw access, it usually picks hdb. Then it tries to finish booting with a mix of Gutsy kernel + Dapper file system. The GUI doesn't work right, but the shell access from a tty works well enough to verify that /dev/hdb1 is mounted as root.

It is not repeatable - if I power cycle the computer and retry, it sometimes picks /dev/hda and everything just works. Reset without a power failure always seemed to fail.

Because the GUI was so broken, I spent a lot of time trouble shooting my X and video driver before it occurred to me to check what drive was actually mounted.

My current work-around is to remove hdb from my system. So far, this has booted correctly 5 out of 5 times, including reset without power cycle.

Brian Murray (brian-murray) wrote :

I strongly suspect that /etc/fstab contains mountpoints like '/dev/sd*' or '/dev/hd*', which is not the recommended way to setup an '/etc/fstab' because device assignments can change between boots. You can learn more about using UUIDs at https://help.ubuntu.com/community/UsingUUID.

Paul Perkins (thirdspace) wrote :

On my computer the problem happened because /etc/fstab contained mountpoints that used UUIDs just as recommended, in fact as set up by the Kubuntu installer and not messed with by me. The problem is that a byte-for-byte copy of a partition has the same UUID as the original partition, even if it is on a different physical drive. Not surprisingly this causes general confusion, especially among Ubuntu's bug-closer crew, who can't wrap their minds around the fact that UUIDs don't quite live up to their name.

Paul Perkins (thirdspace) wrote :

I'm annoyed that Ubuntu is resorting to cooking their statistics by closing bugs as invalid just because they can't be bothered to read them.

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