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

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

Post by johan antwe » Mon, 23 Jun 2003 01:42:40



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?

 
 
 

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

Post by Steven G. Kar » Mon, 23 Jun 2003 02:34:25




Quote:> 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.

> 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?

/dev/ad0 isn't a filesystem, so fsck could not find a
super block, so it reported an error.

--
Steve

 
 
 

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

Post by llewell » Mon, 23 Jun 2003 12:17:44



> 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.

Maaybe you should be running something like 'fsck -p /dev/ad0s1a'
    instead? /dev/ad0 is the whole disk, and normally contains
    multiple filesystems. df(1) and mount(8) list device names that
    map directly to (mounted) filesystems.

Quote:> 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?

[snip]
 
 
 

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

Post by johan antwe » Mon, 23 Jun 2003 22:26:31


Thank you, both of your replies worked. Its one of those things that
seems obvious looking back on it but, when theres no experience with a
utility its easy to overlook. Especially when there's no error message
like "that's not a file system you just asked me to check" or "I don't
recognize this as a file system" or anything more intuitive than
appearing to work correctly and reporting a plausible error message.
 
 
 

1. HELP: BAD SUPER BLOCK: MAGIC NUMBER WRONG

Any ideas of how to gain access to this disk?  I receive the following
error message:

from "fsck -y -o b=$alt_super_block /dev/rdsk/c0t4d0s5"

where $alt_super_block equals every listed superblock.

I've tried the following:

1) All superblocks (found w/nfs -Nv ...)
2) Power cycled disk
3) Shut down all power
4) Open unit and tapped, and I can hear it spin-up & see disk access
light

Any ideas are appreciated---please email responses and I'll consolidate
with a final post to this string.

Regards,


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