Advertisement


F10 F10TROUBLESHOOT HDDBOOT BOOTERRORS RESTORE LILOBOOT HOME PAGE

Back to Top
B o o t   E r r o r s

Here are some errors I generated:

Bootable system from the hard drive, good bootable floppy w/kernel, win95 boot disk w/ fdisk, bootnet.img installation diskette(RH6.2), clean MBR, LILO installed on /boot (primary partition marked active).

     fdisk -l /dev/sda

     Disk /dev/sda: 64 heads, 32 sectors, 1001 cylinders
     Units = cylinders of 2048 * 512 bytes

        Device Boot    Start       End    Blocks   Id  System
     /dev/sda1   *        33        63     31744   83  Linux
     /dev/sda2            64      1001    960512    5  Extended
     /dev/sda3             1        32     32752   12  Compaq diagnostics
     /dev/sda5            64       264    205808   82  Linux swap
     /dev/sda6           265      1001    754672   83  Linux
     


Back to Top
N o   A c t i v e   P a r t i t i o n

No active partition, clean MBR:

I made /boot no longer active and I received the following message on boot up:
     Non-System disk or disk error
     replace and strike any key when ready
     _
     
I booted to my Linux boot disk for my system and marked it active again. System booted just fine.


Back to Top
C o r r u p t   B o o t   S e c t o r  
o n   A c t i v e   P a r t i t i o n

Boot Sector on active partition is corrupt, clean MBR:

I zero'd out the boot sector on /boot and received the following message on boot up:
     Missing operating system
     
I booted to my Linux boot disk for my system and reran /sbin/lilo -v. System booted just fine.


Back to Top
C o r r u p t   M a s t e r   B o o t   R e c o r d

Boot Sector on active partition is corrupt, clean MBR:

I then zero'd out the MBR and got the following message:
     Non-System disk or disk error
     replace and strike any key when ready
     _
     
I then booted to my Linux boot diskette. After it loaded the SCSI driver from the diskette, I received:
     SCSI device sda: hdwr sector= 512 bytes. Sectors= 2051000 [1001 MB] [1.0GB]
      sda: unknown partition table
     autodetecting RAID arrays
     autorun ...
     ... autorun DONE.
     VFS: Cannon open root device 08:06
     Kernel panic: VFS: Unable to mount root fs on 08:06
     
I then booted to my Linux network installation diskette (bootnet.img). Found the NIC, found the SCSI driver, went through custom. Custom showed the following message:
              Bad Partition Table

     The partition table on device sda is 
     corrupted.  To create new partitions 
     it must be initialized, causing the 
     loss of ALL DATA on this drive.
       "INITIALIZE"        "SKIP DRIVE"
     
Looking over at Alt+F4 I see:
     SCSI device sda: hdwr sector= 512 bytes. Sectors= 2051000 [1001 MB] [1.0GB]
      sda: unknown partition table
     
I switched over to the BASH screen (Alt+F2) and ran fdisk:
     fdisk /tmp/sda
     Device contains neither a valid DOS partition table, nor Sun or SGI disklabel
     Building a new DOS disklabel.  Changes will remain in memory only,
     until you decide to write them.  After that, of course, the previous
     content won't be recoverable.

     Command (m for help):  _
     
Printing the partition gives the following result:
     Disk /tmp/sda: 33 heads, 61 sectors, 1018 cylinders
     Units = cylinders of 2013 * 512 bytes

        Device Boot    Start       End    Blocks   Id  System
     
I created the partitions exactly as they existed before (I printed out a listing of the partitions before I zero'd the MBR.); however, the drive geometry is different.
Here is the new printout from fdisk:
     Disk /tmp/sda: 33 heads, 61 sectors, 1018 cylinders
     Units = cylinders of 2013 * 512 bytes

        Device Boot    Start       End    Blocks   Id  System
     /tmp/sda1   *        33        63     31744   83  Linux
     /tmp/sda2            64      1001    960512    5  Extended
     /tmp/sda3             1        32     32752   12  Compaq diagnostics
     /tmp/sda5            64       264    205808   82  Linux swap
     /tmp/sda6           265      1001    754672   83  Linux
     
I wrote this out and rebooted. The geometry of the two do not match; however, I want to see if it will come up. I received the blinking cursor in the upper left corner on the next boot up.
     _
     

After reading the man page on fdisk for Linux, I realized that it will assume its own geometry if fdisk for Linux is the first utility to partition the disk. In my example, where I have no partitions, fdisk for Linux created its own geometry assignments.

I then zero'd out the MBR (ran through network install up to the point where the SCSI driver was loaded, I inserted an ext2 floppy containing dd, mounted it [mknod /tmp/fd0 b 2 0; mkdir /adir; mount /tmp/fd0 /adir], and then zero'd the MBR).

After zeroing the MBR, I ran win95 fdisk /mbr.

After running Win95's fdisk /mbr, I then recreated the fdisk partitions using Linux (again, using the RedHat 6.2 installation CD to do this). Here's a listing of partitions under Linux after zeroing the MBR, and running Win95's fdisk /mbr:
     Command (m for help): p

     Disk /tmp/sda: 64 heads, 32 sectors, 1001 cylinders
     Units = cylinders of 2048 * 512 bytes

        Device Boot    Start       End    Blocks   Id  System
     /tmp/sda1   *         1      1001   1025008    e  Win95 FAT16 (LBA)

     Command (m for help): _
     
After deleting this partition and recreating the partitions exactly as before, here's a printout again of the correct partitions on my hard drive (and the correct geometry):
     Command (m for help): p

     Disk /tmp/sda: 64 heads, 32 sectors, 1001 cylinders
     Units = cylinders of 2048 * 512 bytes

        Device Boot    Start       End    Blocks   Id  System
     /tmp/sda1   *        33        63     31744   83  Linux
     /tmp/sda2            64      1001    960512    5  Extended
     /tmp/sda3             1        32     32752   12  Compaq diagnostics
     /tmp/sda5            64       264    205808   82  Linux swap
     /tmp/sda6           265      1001    754672   83  Linux
     
I wrote this table out and rebooted. The system came up just fine once again off of the hard drive.


********Currently working on this section********

so in desaster recovery, you need to know the drive geometry, a partition printout with starting and ending cylinder values and partition types, a copy of your /etc/fstab, /etc/lilo.conf.


********Currently working on this section********

I then booted to a Win95 boot disk and ran "fdisk /mbr" and got the following message:
Starting MS-DOS
I then booted back to Linux and reran "/sbin/lilo" and got the following message: The following error was generated by having a zero'd out MBR:
     Non-System disk or disk error
     replace and strike any key when ready
     _
    
Also /sbin/lilo complained with the following message: To remedy this, use fdisk to mark the /boot partition active.

After correcting this
Starting MS-DOS...
Oops, I guess the MBR contains the partition table as well...

Back to Top
P R E C A U T I O N A R Y   S T E P S   T O   T A K E   B E F O R E
  A L T E R I N G   T H E   M B R

Preparation steps to take before altering the MBR:





















This section below is under construction. I don't have time to finish it up now, but the information above is pretty valuable, so I decided to go ahead and push what I have to the web.


********Currently working on this section********

so in desaster recovery, you need to know the drive geometry, a partition printout with starting and ending cylinder values and partition types, a copy of your /etc/fstab, /etc/lilo.conf.


********Currently working on this section********

I then booted to a Win95 boot disk and ran "fdisk /mbr" and got the following message:
Starting MS-DOS
I then booted back to Linux and reran "/sbin/lilo" and got the following message: The following error was generated by having a zero'd out MBR:
     Non-System disk or disk error
     replace and strike any key when ready
     _
    
Also /sbin/lilo complained with the following message: To remedy this, use fdisk to mark the /boot partition active.

After correcting this
Starting MS-DOS...
Oops, I guess the MBR contains the partition table as well...