| View previous topic :: View next topic |
| Author |
Message |
nsh
n00b
Joined: 25 Nov 2012
Posts: 5
|
 Posted: Sun Nov 25, 2012 3:47 am Post subject: BIOS does not detect bootable disk (GRUB2) [SOLVED] |
 |
|
Hi,
I have software RAID1 installed (booting using mdadm nomdraid nolvm) on 2 disks-system.
I installed Grub2 and my BIOS does not recognize either of disks as bootable, displaying on load "A bootable device has not been detected".
However, when on startup I get to BIOS boot menu and choose the disk, Gentoo loads.
I followed Gentoo GRUB2 HOWTO to install Grub2.
Grub2 config and data reside in /boot/grub2 (/boot is a raid1 partition, mapped to /dev/md121)
I created a small partition in the beginning of each disk (parted mkpart s34..1048k), set bios_grub flag on it and ran grub2-install /dev/sda as well as grub2-install /dev/sdb to have it on the mirror disk.
UEFI boot in BIOS is disabled.
Could you please advise, what did I mess up/forgot?
Thanks in advance.
Last edited by nsh on Sun Nov 25, 2012 7:49 pm; edited 1 time in total |
|
| Back to top |
|
 |
NeddySeagoon
Administrator
Joined: 05 Jul 2003
Posts: 54208
Location: 56N 3W
|
| Posted: Sun Nov 25, 2012 1:26 pm Post subject: |
|
|
nsh,
Welcome to Gentoo.
Some brain dead BIOS check for the bootable flag on one partition on the boot drive. So your fdisk -l output needs to look like | Code: | Device Boot Start End Blocks Id System
/dev/sda1 * 63 80324 40131 fd Linux raid autodetect
/dev/sda2 80325 1124549 522112+ 82 Linux swap / Solaris
/dev/sda4 1124550 1953520064 976197757+ 5 Extended
/dev/sda5 1124613 11631059 5253223+ fd Linux raid autodetect
/dev/sda6 11631123 1953520064 970944471 fd Linux raid autodetect |
notice the * under bootable.
BIOSes vary. Some don't check at all. Some demand that exactly one partition is marked bootable, others are OK with one or more.
Use fdisk to set the bootable flag on the boot partition of both of the drives in your raid set. Its exactly one bit in the partition table entry for that partition. Your install will not be harmed.
The step is in the Gentoo Handbook
_________________
Regards,
NeddySeagoon
Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail. |
|
| Back to top |
|
|
nsh
n00b
Joined: 25 Nov 2012
Posts: 5
|
| Posted: Sun Nov 25, 2012 6:50 pm Post subject: |
|
|
NeddySeagoon,
Thank you for the reply.
I used parted as I partitioned my disks with GPT, fdisk reports that it does not support GPT.
| Code: | parted
GNU Parted 3.1
Using /dev/sda
Welcome to GNU Parted! Type 'help' to view a list of commands.
(parted) p
Model: ATA WDC WD1002FAEX-0 (scsi)
Disk /dev/sda: 1000GB
Sector size (logical/physical): 512B/512B
Partition Table: gpt
Disk Flags:
8 17.4kB 1048kB 1031kB [GRUB] bios_grub
1 1049kB 1000MB 999MB /boot boot
2 1000MB 34.0GB 33.0GB swap
3 34.0GB 134GB 100GB /usr
4 134GB 144GB 10.0GB /tmp
5 144GB 194GB 50.0GB /var
6 194GB 204GB 10.0GB /
7 204GB 1000GB 796GB /home
|
The same is for /dev/sdb .
I set boot flag on /boot but it doesn't seem to be enough.  
It is HP desktop with DH67BL motherboard. It had RAID support but I disabled it in BIOS as well as UEFI boot. |
|
| Back to top |
|
|
NeddySeagoon
Administrator
Joined: 05 Jul 2003
Posts: 54208
Location: 56N 3W
|
| Posted: Sun Nov 25, 2012 7:01 pm Post subject: |
|
|
nsh,
Ahhh.
You actually have two partition tables on your drives.
A legacy MSDOS partition table in Logical Block 0, which is what your BIOS will see and a GPT partition table used by everything else.
If you ignore fdisks dire warnings about not supporting GPT, it will show that you have a single partition of type EE (from memory) filling the entire disk.
This is how fdisk knows that it does not support your partition table.
However, this is where you need to set the bootable flag, not on your boot partition inside the GPT.
Go ahead and use fdisk to set the bootable flag on your protective MSDOS partition, so that the BIOS can see it.
_________________
Regards,
NeddySeagoon
Computer users fall into two groups:-
those that do backups
those that have never had a hard drive fail. |
|
| Back to top |
|
|
nsh
n00b
Joined: 25 Nov 2012
Posts: 5
|
| Posted: Sun Nov 25, 2012 7:46 pm Post subject: |
|
|
NeddySeagoon,
That makes perfect sense, thank you.
And it worked, too! 
Thanks a lot!
-nsh |
|
| Back to top |
|
|
|
Installing Gentoo
