Date: Wed, 26 Jul 2000 21:44:01 +0200 From: Gerhard Sittig <Gerhard.Sittig@gmx.net> To: stable@FreeBSD.ORG Subject: Re: URGENT: bad superblock Message-ID: <20000726214401.K24476@speedy.gsinet> In-Reply-To: <20000726172005.A79537@chuggalug.clues.com>; from geoffb@chuggalug.clues.com on Wed, Jul 26, 2000 at 05:20:05PM %2B0100 References: <4.3.2.7.2.20000726110451.02e6ef00@msm.cl> <20000726172005.A79537@chuggalug.clues.com>
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On Wed, Jul 26, 2000 at 17:20 +0100, Geoff Buckingham wrote:
> On Wed, Jul 26, 2000 at 11:13:05AM -0400, Marcelo J. Iturbe wrote:
> >
> > Running FreeBSD 3.3 I have the following scenario:
> > The filesystem won't boot.
> > When I try to mount (/dev/da0s2) it from an emergency boot disk I get a
> > "Incorrect Superblock" error.
> > When I try to run fsck it gives me an error about wrong magic number.
> > Here is the partition information
>
> What kind of file system is this? (ie ffs or FAT16/32)
> If it is ufs/ffs are you specifying a partition as well as a slice?
>
> example command line>mount /dev/da0s2a /mnt
Which turns out to be a little hard sometimes (been there with
the 4.0 CD set this week) when the fixit media doesn't have slice
entries in /dev and you don't have access to the (yet to be
mounted!) filesystem with the appropriate /dev entries. Funnily
ad0s1 happily gets mounted when it regularly should be ad0s1a,
later I found that the minor numbers are the same for them. But
the fixit prompts never would let me access slices other than *a.
And it took quite some time to find the minors' numbering (I
finally found it when reading disklabel(5) for completely other
reasons). Once this is known you can mknod(8) whatever you need
at the fixit prompt.
Returning to the problem: From L*'s ext2fs I know of a method to
fallback to the superblock's copies sprinkled all over the disk
(every 8192 blocks?) when the "first" one is damaged. This info
could at least be used to restore the first one to make mount
work again. Is there some similar mechanism for ffs/ufs?
virtually yours 82D1 9B9C 01DC 4FB4 D7B4 61BE 3F49 4F77 72DE DA76
Gerhard Sittig true | mail -s "get gpg key" Gerhard.Sittig@gmx.net
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