Bad Super Block Wrong magic number

Bad Super Block Wrong magic number

Post by Pat McPartlan » Wed, 15 May 1996 04:00:00



My system crashed while trying to do a dump to the tape drive.  I get
a "bad super block magic number wrong" message that fsck can't fix.  
Is there a way to fix this without killing all my files?

Pat McPartland

 
 
 

Bad Super Block Wrong magic number

Post by Wilko Bul » Thu, 16 May 1996 04:00:00



>My system crashed while trying to do a dump to the tape drive.  I get
>a "bad super block magic number wrong" message that fsck can't fix.  
>Is there a way to fix this without killing all my files?

Probably. The FFS keeps multiple copies of the superblock. To
find out where the additional copies of the superblock are use
newfs -N /dev/whatever (DON'T FORGET the -N, and check the man
page to see what it does).

The superblock# are now printed. You can subsequently run
fsck -b # where # is one of the block# printed by newfs -N

Hope this helps

Wilko

 
 
 

Bad Super Block Wrong magic number

Post by J Wuns » Thu, 16 May 1996 04:00:00



> My system crashed while trying to do a dump to the tape drive.  I get
> a "bad super block magic number wrong" message that fsck can't fix.  
> Is there a way to fix this without killing all my files?

The fixit floppy, and a backup tape.  If your root file system is
still intact, you perhaps don't need the fixit floppy (since you can
boot single-user, and try to fix the problem).

There's an fsdb around (it went to /xperimnt in 2.1R and is in the
base system in the 2.2 development sources), but it's perhaps rather
tricky to use it.  Try if you can use alternate superblocks (fsck -b
32).

--
cheers, J"org


Never trust an operating system you don't have sources for. ;-)

 
 
 

1. functioning file system with "bad super block: magic number wrong"?

Re-installed 4.8 after formatting the disk. Just as a test, went down
to single-user mode, un-mounted all the file systems, and ran fsck
which reported no problems. For curiosity, I ran fsck -p /dev/ad0. It
reported that there was a "bad super block: magic number wrong" and
unexpected inconsistency: run fsck manually.

This message was ignored and the system was rebooted with no problems.
A new kernel was built and no problems occurred. It seems that the
file system is working perfectly well, in spite of this "bad super
block".

The question is, is it normal to have some trivial errors be reported
by fsck at any given invocation? Is there nothing wrong with my file
system?

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