Proliant boots with MBR, but not GPT [SOLVED]

Fog_Watch · Last edited by Fog_Watch on Wed Oct 03, 2012 6:40 am; edited 1 time in total

Hello

I have a PATA drive attached to a Proliant DL380 G5 via a JMicron
chipset. If I partition the drive with a MBR the machine boots. With
the same installation files and same disk, only this time partitioned
with a GPT, the boot process detects the attached drive and then hangs
with a depressing "unable to mount root fs on unknown block(8,3)".

In a simlar thread:

VoidMage · Watchman Joined: 14 Oct 2006 Posts: 6196

Well, as the kernel is 3.3.8, did you try booting by PARTUUID ?

darkphader · Veteran Joined: 09 May 2002 Posts: 1217 Location: Motown

Did you create a bios boot partition, a type ef02 raw (no file system) partition, on the GPT disk?

EDIT: sorry, I see that you did.

Might also need to use fdisk to mark the bootable partition (even though your symptoms are different) as in:
http://blog.realcomputerguy.com/2012/03/no-bootable-device-gpt.html

EDIT 2:
Is this set (don't know if it's necessary but I use it)?
CONFIG_BLK_DEV_BSG=y

EDIT 3:
Assuming SATA drive is this set and the BIOS set for AHCI as well?
CONFIG_SATA_AHCI=y
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NeddySeagoon · Posted: Mon Oct 01, 2012 6:57 pm Post subject:

Fog_Watch,

I use grub1 and GPT. There is a minor trap for the unwary, not during the install but during updates.

With grub1 and GPT, there is no place to install the stage1.5 loader, so stage1 loads stage2 directly from a block list.
If stage2 moves around on the filesystem, e.g. grub is updated, you MUST install grub to the MBR again or horrible things may happen, since the stage1 needs a new blocklist to find the new stage2 file. It will quite happily use the stage2 in the free space until a kernel update overwrites it. Ask any lilo user.

The BIOS can't read GPT ... but it doesn't need to, it only reads the MBR.
IF your BIOS is brain dead an needs the bootable flag set, set it on the protective MSDOS Partition, ont on any of the GPT partitions.
_________________
Regards,

NeddySeagoon

Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail.

Fog_Watch · Posted: Wed Oct 03, 2012 6:40 am Post subject:

When I was experiencing this problem I was booting with grml32_2011.12.iso. When I switched to systemrescuecd-x86-3.0.0.iso the machine then booted. I'm not saying that GRML was the problem and SystemRescueCD was the solution, its just that at around about this time I was able to boot. Sorry I can't be more definitive. Anyway, this is enough to mark this solved.

Thanks again for your contributions.