"Cannot find file system superblock" error - how to recover?
Sergey 'DoubleF' Zaharchenko
doublef at tele-kom.ru
Tue Jan 6 07:31:28 PST 2004
On Tue, 6 Jan 2004 06:31:08 -0800 (PST)
"Scott I. Remick" <scott at sremick.net> probably wrote:
>
> --- Sergey 'DoubleF' Zaharchenko <doublef at tele-kom.ru> wrote:
> > And maybe prefix that by a
> >
> > $ bsdlabel -R /dev/ad6s1c dislabel.ad6s1c.new
Sorry that was to be $ bsdlabel -R -n /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.
>
A little before that the manual says:
> Disk device name
> All disklabel forms require a disk device name, which should always be
> the raw device name representing the disk or slice. For example da0 rep-
> resents the entire disk regardless of any DOS partitioning, and da0s1
> represents a slice. Some devices, most notably ccd, require that the
So that da0 is just an example, albeit a perverted one.
> > 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
The one you sent the last time (with the 0-s).
> 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.
>
It confuses me too.
> > 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
Indeed it's not like in 4.x, where they were the same. And what about
# ls -l /dev/ad6s1a /dev/ad6s1b
(these minor numbers don't seem to be in order).
Anyway, the correct beginning for the filesystem is 0 (starting with
ad6s1), as the superblock is 16 sectors from there.
> 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
Indeed. I'm confused. 5.x doesn't look like 4.x.
2 different(?) labels on the same slice don't look good to me (or are
the nubers just calculated differently?).
I will probably download some 5.1 boot floppies to reproduce the
situation.
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--
DoubleF
Speak softly and carry a +6 two-handed sword.
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