Raid 5, >2TB, GPT, Grub, booting, mounting root
 

Greetings,

Wow, this has been a hell of a journey, one where RedHat gave up...but I'm not ready too, just yet, but I'm close.

Here's the Setup:
6 WD 500GB Drives connected to a Areca card
1 huge 2.5TB Raid5 GPT Array


Installed RHEL5 just fine but upon reboot it shat itself in the most messy, smelly and offensive fashion.

Struggled half-assed for a few weeks and found nothing easy. Pulled up my bootstraps, opened a case with RedHat and dug in. I quickly found that grub was the offender in the sense that it can not deal with GPT partitions. RedHat didn't know that or at least the guy I was working with didn't. He went off in his lab to prove me wrong.

I then found a patch/hack for grub that with a little massaging, sweet talking, promises of long vacations and nights on the town dancing till dawn it ACTUALLY WORKED!!! Causeing me to shat myself in a similar fashion. RedHat knob called to verify that grub couldnt deal with >2TB partitions which prompted me to say, what are you talking about, I'm booting right now (I couldn't resist), just as I heard his voice crack I realized my little prank was about to go to far so I attached the patch/hack to the case, off he went back into his lab.

So asside from some embarressing digestive setbacks everything should be cool right? Well, now the system panics because it's unable to mount root which is a LV. I booted into rescue mode and did everything I knew to do and everything looked hunkie dorrie.

RedHat called back now with the official stance that this is unsupported and that was that, so they gave up.

Any ideas?

Could the problem still be with grub even though /boot (which is a part of the 2.5TB array) mounts just fine and the kernel loads?

I know very little about LVM, what can I do to get root to mount upon boot?

Hard to say (and I don't have a lab where I could test your setup) :}

I assume you have an initrd that supports LVM and your file-system
of choice to begin with?



Cheers,
Tink

Hey....well I finally got it. This was more of an excersize in frustration and futility then anything because NOTHING MADE/MAKES any sense...ill try to explain.

1. Initial install of RHEL5 THAT REQUIRED A DRIVER DISK FOR MY ARECA raid controller that completed without a hitch
2. Reboot Fails
3. Brief troubleshooting found grub's inablity to work with >2TB filesysems to be the problem
4. Lots of luck revealed a patch to grub which fixed grub, quite impressively I might add.
5. Reboot presented the problem outline in this post.

Ok, so I've spent mucho time on this and the prolem ended up being that the initrd image - NOR - the stock install had the driver for my raid card ANYWHERE. which begs the question, HOW THE HELL DID THIS 2.7TB array end up with RHEL5 on it?

The simple fix was to:
1. copy the driver to /lib/modules/uname -a/kernel/drivers/scsi/
2. rerun depmod
3. run mkinitrd
4. reboot

For someone haveing this same prob, do the following:
1. linux rescue dd
2. cp /tmp/(your scsi driver) /mnt/sysimage/lib/modules/(your kernel)/kernel/drivers/scsi
3. depmod -a
4. mkinitrd -f -v /boot/(your initrd) (your kernel)
5. reboot

Errors
 

depmod worked when I used "depmod -a -b /mnt/sysimage/

but mkinitrd -f -v /mnt/sysimage/boot/initrd-2.6.18-8.el5.img /mnt/sysimage/lib/modules/2.6.18-8.el5/ fails with the error "No modules available for kernel "......" and not sure where I am going wrong with the syntax.


j

Error
 

I was able to follow your advice by the following:

1. linux rescue dd
2. cp /tmp/(your scsi driver) /mnt/sysimage/lib/modules/(your kernel)/kernel/drivers/scsi
3. chroot /mnt/sysimage
4. depmod -a
5. mkinitrd -f -v /boot/(your initrd) (your kernel)
6. reboot

Although after the reboot I received the same error... and stuck like chuck.

j

jon0996, man I feel for you...let me think....if im not mistaken the biggest issue I faced with this was that in rescue mode the "running kernel" was not the same as either of standard booting kernels and I had to do some finagling to get it to work. Also, you have to be sure to have the kernel sources installed if I'm not mistaken which is NO SMALL TASK unless you REALLY got your sheit together or just went through that battle, IMHO the powers that be really fuked up by not includeing that in standard installs anymore.

Please let me know how it's going, I certainly will help you through this if need be.

Hey man, i guess I didnt refresh my page....what exactly is going on? tell me more about your setup and error?

One quick question...when you completed the following step

5. mkinitrd -f -v /boot/(your initrd) (your kernel)

DID YOU SEE IT ADD YOUR SCSI MODULE to the initrd? If not, then that's the issue. If so, then it might be another issue like grub or something, but for me to be sure, I need to know more about the error your getting.

Hope this helps, and to hear from you soon.