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Corrupt MBR
Posted: 14. Jul 2017, 08:32
by Atip
If the MBR is corrupted can it be repaired.
Sofar my attempts fail.
Code: Select all
sudo e2fsck /dev/sda
e2fsck 1.43.1 (08-Jun-2016)
ext2fs_open2: Bad magic number in super-block
e2fsck: Superblock invalid, trying backup blocks...
e2fsck: Bad magic number in super-block while trying to open /dev/sda
The superblock could not be read or does not describe a valid ext2/ext3/ext4
filesystem. If the device is valid and it really contains an ext2/ext3/ext4
filesystem (and not swap or ufs or something else), then the superblock
is corrupt, and you might try running e2fsck with an alternate superblock:
e2fsck -b 8193 <device>
or
e2fsck -b 32768 <device>
/dev/sda contains `DOS/MBR boot sector, LInux i386 boot LOader; partition 1 : ID=0x82, start-CHS (0x0,1,1), end-CHS (0x2,254,63), startsector 63, 48132 sectors; partition 2 : ID=0x82, start-CHS (0x3,0,1), end-CHS (0x5,254,63), startsector 48195, 48195 sectors; partition 3 : ID=0x5, start-CHS (0x6,0,62), end-CHS (0x3ff,254,63), startsector 96451, 156204861 sectors' data
Tried those alternate superblocks and nothing changes.
Suggestions appreciated.
Re: Corrupt MBR
Posted: 14. Jul 2017, 10:08
by laprjns
Have you tried reinstalling the mbr using lilo?
Re: Corrupt MBR
Posted: 14. Jul 2017, 10:18
by DidierSpaier
File systems are inside partitions, not partitioned devices.
Assuming that you have a not mounted partition named /dev/sda1 for instance, type:
Re: Corrupt MBR
Posted: 15. Jul 2017, 06:42
by Atip
Thanks all!
laprjns
Yes I did a few times. Nothing doing.
DidierSpaier
Good hint. Deleted sda1, put it back all using fdisk. Run lilo and MBR is back in action.
For such occasions it is handy to have a slackware USB boot stick.
Best
Re: Corrupt MBR
Posted: 15. Jul 2017, 07:54
by DidierSpaier
For the records: your MBR was most probably
not corrupted. If it were you couldn't have booted at all. Maybe the filesystem in /dev/sda1 was corrupted (in which case e2fsck could have been used to repair it), we will never know as you didn't post the output of "sudo e2fsck /dev/sda1" before wiping out its content.
Actually, you didn't even tell why you felt the need to run this e2fsck command in your first post. Maybe nothing was corrupted
Re: Corrupt MBR
Posted: 16. Jul 2017, 02:23
by Atip
Well I could not boot anymore to any of my bootable partitions. The display acted abnormal and booting would stop with kernel panic I think. Could, however, boot with slackware boot stick. Running lilo did not help and gave no errors.
Thinking that MBR resides in /dev/sda above /dev/sda1, therefore, I did not do e2fsck /dev/sda1.
After fixing /dev/sda1 all is well now.