Re: e2fsck error
On Fri, 3 Aug 2001, Gene Grimm wrote:
> Bart-Jan Vrielink wrote:
> > On Thu, 2 Aug 2001, Gene Grimm wrote:
> > > > A short while ago, my web server went offline and is now reporting a
> > > > superblock error on /dev/hdc1 (/var) and suggests using e2fsck -b
> > > > 8193 option. I do not know enough about the ext2 system to know
> > > > what super block numbers to try. Can anyone suggest the correct
> > > > numbers or how to find out? This is a personal web server plus I use
> > > > this to test configurations.
> > > >
> > > To follow up, I have tried several numbers from 8193 incrementing by
> > > 8192, and they all report something like invalid magic number in super
> > > block.
> > >
> > Please read the e2fsck manpage. The exact position of the backup
> > superblock depends on the blocksize of your filesystem. You can find the
> > blocksize by running dumpe2fs -h /dev/hdc1| grep "Block size"
> dumpe2fs -h /dev/hdc1 reports:
> Bad magic number in super-block while trying to open /dev/hdc1.
> Couldn't find valid filesystem superblock.
> Since I don't know much about the ext2 file system, I am afraid to use the
> debugfs utility without specific guidence.
Sorry, my mistake (dumpe2fs uses the first superblock to get it's
If the filesystem was initialized with mke2fs using the default settings
it's very likely that it's using a 4k blocksize, so the backup superblock
should be at 32768.
If you're afraid to use tools you're not familiar with on that filesystem,
why not copy that filesystem to a file using dd and test the tools on that
file first ??