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From: "Rodney W. Grimes" <rgrimes@GndRsh.aac.dev.com>
Message-Id: <199605041028.DAA01172@GndRsh.aac.dev.com>
Subject: Re: ccd offset, please review + test
To: asami@cs.berkeley.edu (Satoshi Asami)
Date: Sat, 4 May 1996 03:28:47 -0700 (PDT)
Cc: current@freebsd.org, ccd@stampede.cs.berkeley.edu
In-Reply-To: <199605031944.MAA29103@silvia.HIP.Berkeley.EDU> from Satoshi Asami at "May 3, 96 12:44:32 pm"
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>  * And /dev/sd237c should _not_ be used.  You should manually go add a
>  * /dev/sd237a and use that for the ccd, this should eliminate your problem.
> 
> For the whole slice, or with an offset?  In other words, is sdXc
> special because of its name, or because it is the only partition that
> starts at the beginning?

It is special because it is RAW_PART.

> 
> Wait, the latter doesn't make sense, all the machines here have the
> root filesystem starting at offset 0 (within the slice).  So you're
> saying sdXc is special because it has the letter `c' in it?

It is special because it is RAW_PART.  The other part of the puzzle is
that newfs saves space for a label/bootstrap when newfs'ing partitions
starting in cylinder 0, so I was wrong, it is safe to use sdXc as a
file system.  It is this protection in newfs that you loose on the ccd.

> 
>  * Conventient, but wrong to do.  UNIX has reserved xxYc for as long as
>  * I can remeber, using it for file systems is a sure fire way to burn
>  * yourself.
> 
> Well I don't think that is true, the SunOS machines I was
> administering back in Tokyo (about 6 years ago) didn't mind us using
> sdXc for the whole disk.

You have lost write protection for your disklabel, not a grand idea...


-- 
Rod Grimes                                      rgrimes@gndrsh.aac.dev.com
Accurate Automation Company                 Reliable computers for FreeBSD