Loading PBR for descriptor 3...done. Bad PBR Sig

[cbryansmith]

After a motherboard failure and replacement a Dell PE 6850, during the first restart, we receive this on running RHEL 4.5:
Loading PBR for descriptor 3...done. Bad PBR Sig.
I would appreciate corrective action for this error.

Also, I have determined PBR to mean "Partition Boot Record." I have not been able to determine what "descriptor 3" is. I would appreciate information on these terms also.

Thanks,
Bryan Smith

[Rubberman]

Are you running a RAID? Or LVM group that spans multiple drives? One presumes you are running the original drives from the failed system? When it failed, is it possible that it munged the disc? IE, perhaps it corrupted the MBR/PBR on the 3rd drive the OS is identifying (possibly /dev/sdc or /dev/sdd, depending upon whether it is using a 0-based index or a 1-based index for the drives). What we need to do is to determine what exactly happened. So, first boot from a live/recovery CD/DVD. Then, after logging in as root to the live CD system, run the command fdisk -l in order to see the partition tables of all the available discs. If one is bad, you might see an error. Try that, and report back here with the output of the command.

[cbryansmith]

Rubberman,
I appreciate your response.

A similar server is partioned as follows.


Disk /dev/sda: 146.5 GB, 146548981760 bytes
255 heads, 63 sectors/track, 17816 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Device Boot Start End Blocks Id System
/dev/sda1 1 4 32098+ de Dell Utility
/dev/sda2 5 6271 50339677+ 83 Linux
/dev/sda3 * 6272 6336 522112+ 83 Linux
/dev/sda4 6337 17816 92213100 5 Extended
/dev/sda5 6337 17816 92213068+ 8e Linux LVM

I'm researching as to how to build a recovery CD. I'm avoiding downloading a "boot disk" from somewhere on the internet. Could you send a URL detailing how to do this?

Thanks again for your help.

[Rubberman]

Some distributions allow you to create a bootable USB (thumb) drive for just such purposes. Alternatively, there are minimal boot/recovery CD images out there that are only 50MB or so in size, so they don't take too long to download provided you have any sort of reasonable internet access speed.