(yet another) Grub2 can't find root block device

[sabayonino]

I see you have /var partition in a separate part and / in other HDD .

I've tried with my gentoo /usr and (or) /var partition but udev seems to have some problems to initialize devices.

http://forums.gentoo.org/viewtopic-p-6871414.html

As many of you will be aware, udev upstream is moving to requiring /usr mounted before it starts. Upstream (including kernel developers) advocates an initramfs across the board for Linux distributions, but definitely in the case where /usr is on a separate partition. This is not down to udev itself, but helper scripts for devices which often live in /usr or sometimes /var, and aiui the hardware database is also on /usr (i guess that bit is down to udev itself;) [...]

If you include /var (and /usr) in / you could solve.

[tollgate]

As I said, our Installer leaves a 1Mb free space at the beginning of any disk since 2008 or even earlier.
Anyway yes, if you upgrade your MBR through grub2-install the system won't boot anymore.

lxnay I get it now. One of my machines had Sabayon installed over a previous Mandriva install and this machine starts sda1 at block 63. However, my 2nd machine which had a totally fresh install of Sabayon 9, does indeed start sda1 at block 2048.

[grimly64]

Everything was fine in the world. Was dual booting with Windows 7 and Sabayon on the same hard drive..... Now the world is in chaos. Wish I had never updated this "rolling release", have never had so many problems. Now my led light for the hard drive is constantly on whether it's Win 7 or Sabayon.

[hulkyboy]

My first disk starts at 63, and since it's a major hassle reinstalling windows 7, I decided to boot from my second disk. So grub2 has been installed to /dev/sdb. I still get prompted for the root device...

Device Boot Start End Blocks Id System
/dev/sdb1 * 4096 83890175 41943040 7 HPFS/NTFS/exFAT
/dev/sdb2 83891430 488392064 202250317+ 7 HPFS/NTFS/exFAT

Anybody got any idea how to fix this?