"Cannot find file system superblock" error - how to recover?

[Scott I. Remick]

--- Sergey 'DoubleF' Zaharchenko <doublef at tele-kom.ru> wrote:
> And maybe prefix that by a
> 
> $ bsdlabel -R /dev/ad6s1c dislabel.ad6s1c.new
> 
> which would just check your new layout for errors, without writing
> anything, and print your file out as disklabel understands it.

So you're saying, run it as user and not root for the sake of testing it in
a read-only setting? Would that be better than using -n? From the man page:

"The -n stops the bsdlabel program right before the disk would have been
modified, and displays the result instead of writing it."

> > > And lastly... your talk about offsets. The man page for bsdlabel
> describes
> > > using it on the whole disk (ad6) and not a slice or partition. If I
> run it
> 
> It can't be fdisk that you are reading about?

Nope. "man bsdlabel" mentions:

"disk represents the disk in question, and may be in the form da0 or
 /dev/da0.  It will display the partition layout."

But I see now all the later examples mention da0s1 so maybe I misunderstood.

> And the `new' one seems to be correct for a 80G drive (+- a couple of
> megabytes)? Have you touched anything?
> 
> Now, mount might work.

Haven't changed anything yet. Which one are you calling the "new" one? Mount
would be done on the partion (ad6s1c) which gives errors with bsdlabel and
has an offset of 63, not the whole slice (ad6s1) which has an offset of 0
and doesn't give errors (with bsdlabel).

> Uhum. disklabel said that the offset was 63 in your previous posting,
> didn't it? 

63 for ad6s1c, 0 for ad6s1. This is what's got Malcolm confused.

> What does
> 
> # ls -l /dev/ad6s1 /dev/ad6s1c
> 
> say? Any differences? I have none.

su-2.05b# ls -l /dev/ad6s1 /dev/ad6s1c
crw-r-----  1 root  operator    4,  20 Dec 29 08:11 /dev/ad6s1
crw-r-----  1 root  operator    4,  21 Dec 29 08:11 /dev/ad6s1c

And to recap:

su-2.05b# bsdlabel /dev/ad6s1
# /dev/ad6s1:
8 partitions:
#        size   offset    fstype   [fsize bsize bps/cpg]
  c: 156344517        0    unused        0     0         # "raw" part, don't
edit
  e: 156344517        0    4.2BSD     2048 16384    89

su-2.05b# bsdlabel /dev/ad6s1c
# /dev/ad6s1c:
8 partitions:
#        size   offset    fstype   [fsize bsize bps/cpg]
  c: 156344517       63    unused        0     0         # "raw" part, don't
edit
  e: 156344517       63    4.2BSD     2048 16384    89
partition c: partition extends past end of unit
bsdlabel: partition c doesn't start at 0!
bsdlabel: An incorrect partition c may cause problems for standard system
utilities
partition e: partition extends past end of unit