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Date: Fri, 18 Aug 95 10:22:07 CDT
Message-Id: <9508181522.AA02468@ihats103.ih.att.com>
To: freebsd-questions@FreeBSD.org
Subject: Re: ** How to add second SCSI disk ? **
Sender: questions-owner@FreeBSD.org
Precedence: bulk


 
> 
> After fdisk and some partition definitions I am getting using
> "disklabel -r sd1":
> 
> # /dev/rsd1c:
> type: SCSI
> disk: sd1s1
> label:
> flags:
> bytes/sector: 512
> sectors/track: 32
> tracks/cylinder: 64
> sectors/cylinder: 2048
> cylinders: 80
> sectors/unit: 165856
> rpm: 0
> interleave: 0
> trackskew: 0
> cylinderskew: 0
> headswitch: 0           # milliseconds
> track-to-track seek: 0  # milliseconds
> drivedata: 0
> 
> 8 partitions:
> #        size   offset    fstype   [fsize bsize bps/cpg]
>   a:   145856    20000    4.2BSD        0     0     0   # (Cyl.    9*- 80*)
>   b:    20000        0      swap                        # (Cyl.    0 - 9*)
>   c:   165856        0    unused        0     0         # (Cyl.    0 - 80*)
> 
  :
  :
> 
> 3. If I change the order to
> 
> #        size   offset    fstype   [fsize bsize bps/cpg]
>   a:   145856        0    4.2BSD        0     0     0   # (Cyl.    9*- 80*)
>   b:    20000   145856      swap                        # (Cyl.    0 - 9*)
>   c:   165856        0    unused        0     0         # (Cyl.    0 - 80*)
> 
> Mount does not accpet it, "/dev/sd1a on /mnt: Incorrect super block.". Why?
> 

As has been mentioned, a file system must be created before one can mount.
However, when I added a new SCSI disk recently, I ran into a problem that I eventually
thought I figured out:  if I put swap at offset 0, then the disklabel info
was written over as soon as the swap was used.  If I put a filesystem at offset
0, then there seems to be some slop at the beginning of the filesystem
which allows the disklabel info to remain and not be written over.

Is this correct or did I somehow fix my problem but completely misunderstand
what was going on?

Dave Bodenstab
imdave@ihats1.ih.att.com