c partition goes away in FreeBSD 8

c partition goes away in FreeBSD 8

FreeBSD 8.0 will soon be released. It promised many new improvments. I’ve been upgrading some of my servers to 8.0 lately. Recently I encountered one interesting problem with disk partitions. It was easily fixed, but I thought I should document it because I know someone else is going to hit it.

Details

Today I upgraded my development server from FreeBSD 7.2 to FreeBSD 8.0-PRERELEASE. I had recently upgraded from 6.4 to 7.2, so I expected no problems upgrading to 8.0, as supported by recent experiences with a few other machines. I was wrong. When rebooting the 8.0 kernel, the system could not find /dev/mirror/gm0s1c. All it saw was:

[dan@ngaio:~] $ ls -l /dev/mirror/
total 0
crw-r-----  1 root  operator    0, 100 Nov 18 23:29 gm0
crw-r-----  1 root  operator    0, 103 Nov 18 23:29 gm0s1
[dan@ngaio:~] $

I altered /etc/fstab to comment out that line and proceeded to boot. That worked. That partition c is no longer present. c was always a “magic” partition in that it existed even without a disklabel and encompassed the entire slice. I altered my /etc/fstab as shown and the mount now works:

13c13
< /dev/mirror/gm0s1c     /wdc   ufs     rw      2       2
---
> /dev/mirror/gm0s1      /wdc   ufs     rw      2       2

That fixed it.