VFS: Could not open root device.....Going INSANE !!

l1nny · n00b Joined: 13 Sep 2006 Posts: 13 Location: USA

VFS: Cannot open root device "<NULL>" or unknown-block (8,20)
Please append a correct "root=" boot option
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown block(8,20)

Okay, I reinstalled Gentoo and thought I was gonna' be so smart, but I'm about to go totally berzerk !!!!
I installed 2006.1 (kernel 2.6.17-r8 ) and have been fighting this insane problem since yesterday !
PC is dual Xeon with 2 sas drives, 1 sata drive, Adaptec 4805 controller.
Installation is on drive 2 (sas) on primary partitions 2,3 & 4 [NTFS partition on 1]. Install was performed following Gentoo.org handbook; genkernel was not used [but I did try it].
Grub.conf:

root (hd1,1)
kernel /boot/bzImage root /dev/sdb3 [have also tried using root (hd1,3)

Installed grub using 1] grub -- root (hd1,1) / setup (hd0) /quit

Fdisk -l confirms my drive configurations.

I know I need at least a couple of Adaptec drivers which I'm sure I'm using in menuconfig, plus several other SATA drivers.

The thing about the above message !! block(8,20) [unless I'm totally mistaken] IS drive 2 (major number) and the minor number -16 is partiton 4 !!! That is the root partition.

Sorry, about to pull my hair out though. I've searched and searched, read & read, and still I keep getting this error.
ANY comments or thoughts very much appreciated. I've tried to give as much info as necessary, but will be glad to give more. BTW, 'don't know if this is pertinent, but this happens right after "md: Autodetecting RAID arrays. / md: autorun ...
/ md: ... autorun DONE."
Thanks.

Voltago · Posted: Fri Sep 22, 2006 10:21 pm Post subject:

Make sure your grub.conf has the '=' like in this code: (your post missed it)

phorn · Tux's lil' helper Joined: 01 Jul 2006 Posts: 109

As shown by ls -l /dev:

l1nny · n00b Joined: 13 Sep 2006 Posts: 13 Location: USA

Still at it, now probably worse than before. I wiped the drives and placed the file systems back on and started from scratch.
Now, I'm getting the old "VFS: Cannot open root device "(hd1,3)" or unknown-block(0,0).
Tried the = Voltago & it didn't seem to matter, but I'll make sure I use it.
And yes, the root is sdb4, which is indicated, but for grub, it's 1 less, right ?
'Not sure what I'm going to do. I've spent days working with KnoppMyth, but this is getting old, getting a system going instead of being able to work with it. I did have the system booting before, but had no network interfaces. 'Wish I'd left well enough alone and worked on getting the network going.....
The drivers needed are aacraid & one I'm not finding in the drivers section (/usr/src/linux.../drivers/scsi). I think there should be a DKM module that I'm not finding, but I'm not sure on that. It's possible another driver is interfering too; I read one post that stated a firewire driver was causing problems kind of like this.
Anyway, I'm through for the night (morning), and will give it a go in a few hours.
BTW, how do I get Adaptec drivers from a disk onto my Gentoo "installation" ? I should have found out how to do that before now. Anyway, this problem is really crazy, and unknown-block(0,0) looks a lot worse than before.
Any further comments or advice appreciated. I've had this machine up one time, and that was using genkernel, which I tried again, hoping it would grab the needed driver; possibly it grabbed too many drivers....
Thanks for the replies.

l1nny · n00b Joined: 13 Sep 2006 Posts: 13 Location: USA

Okay, I was reading Genkernel's docs and it stated that "real_root=/dev/sdb3" was necessary; I also added the initramfs line, and did get to "Activating mdev / Determining root device... / !! Block device /dev/sdb3 is not a valid root device..
!! The root block device is unspecified or not detected. / Please specify a device to boot, or "shell" for a shell..."
Well, maybe there are possiblities here. 'Will check it out later a.m....

l1nny · n00b Joined: 13 Sep 2006 Posts: 13 Location: USA

Okay, progress back to the original error message, panic @ block(8,20) now. Left off the initramfs and just used real_root
in grub, like so: kernel /boot/bzImage root=(hd1,1) real_root=(hd1,3)
I'm not sure why the cdrom is mounted as " 'filesystem' /dev/hda ,,,,,,,, /mnt/cdrom ", and this is used in fstab.
Lost, totally. Any ideals, please post.
Thanks.

sonicbhoc · Posted: Sat Sep 23, 2006 2:38 pm Post subject:

kernel /boot/bzImage root=(hd1,1) real_root=(hd1,3)
NO NO NO.

You have to set it to say /dev/hdb2 real_root=/dev/hdb3

also, remember hda = hd0 in grub. You have to subract everything by one.

hda1 = (hd0,0)

l1nny · n00b Joined: 13 Sep 2006 Posts: 13 Location: USA

Right, I think I understand that, hopefully. 'Fixing to try it again like that; just booted up using the initramfs line again and came up with the same old "root block device not found"....
But, to make sure you understand the partitioning scheme, the Linux partitions are on sdb [1 in grub-speak], and are partitions:
1 Win NTFS
2 /boot,
3 swap,
4 / root
(dev's/sdb2,3,4).
Okay, just tried it like that, I honestly don't know where to turn now; I really should have kept the good install I had w/o the
networking...spilled milk...
Anyway, just tried it as you posted it and still I come to the infamous
>>Activatiing mdev
>> Determining root device...
!! Block device /dev/sdb3 is not a valid root device....
!! The root block device is unspecified or not detected.
Please specify a device to boot, or '"shell" for a shell...
boot( ) ::

Is there any possiblity that fstab or mtab could be causing problems ? Not sure where to look at this point...
Try, try again and again.
Thanks for the reply.

sonicbhoc · Posted: Sat Sep 23, 2006 4:00 pm Post subject:

the fstab is definitely a possibility.

I've never heard of mdev before. Are you using Genkernel? just make your own kernel from scratch, you'll have a lot less headaches in the future. Trust me.

mvantuyl · Posted: Sat Sep 23, 2006 4:14 pm Post subject: Re: Dumb & Dumber....:)

corsair · Posted: Sat Sep 23, 2006 5:12 pm Post subject:

also make sure the necessary options for your ide drive are compiled in. this is described in the gentoo handbook: http://www.gentoo.org/doc/en/handbook/handbook-x86.xml?part=1&chap=7#doc_chap3

regards, corsair

javlinz · n00b Joined: 15 Nov 2003 Posts: 29

l1nny · n00b Joined: 13 Sep 2006 Posts: 13 Location: USA

I really appreciate the help & comments, and I did read the genkernel documentation regarding grub, and set it up exactly as was stated (using a ramdisk, udev, .....). Still the same screen.
To be honest, I'd rather use the manual kernel configuration anyway; that's the way I did it before except for the first time. It'll probably be a lot less painful, and I'll end up with a leaner kernel w/o loading every driver & module in the known Linux universe

.
I just did a file system check on the root & boot partitions just to make sure, but they came up clean.
Again, thanks. I really like to solve my own problems if possible, but this just isn't going anywhere quick enough, so I'm fixing to start from scratch.