Path: utzoo!attcan!uunet!samsung!zaphod.mps.ohio-state.edu!usc!wuarchive!udel!new
From: new@udel.edu (Darren New)
Newsgroups: comp.sys.amiga
Subject: Re: DH0: Disk Validation Error
Message-ID: <14798@nigel.udel.EDU>
Date: 23 Mar 90 17:35:25 GMT
References: <32.25FF9483@alake.FIDONET.ORG> <1990Mar17.225353.24099@uokmax.uucp> <1809@gannet.cl.cam.ac.uk> <3279@alva.tut.fi> <11922@etana.tut.fi>
Sender: usenet@udel.EDU
Reply-To: new@udel.edu (Darren New)
Organization: University of Delaware
Lines: 35

In article <11922@etana.tut.fi> po87553@metso.tut.fi (Ojala Pasi Juhani) writes:
>[...] The disk may well be out of order, but disk validator doesn't
>notice that because it can't do anythink to disk which is formatted with
>inhibit-option.

Not quite.  The INHIBIT option tells the filesystem to ignore the disk
between the time the FORMAT program starts until the time the format 
program ends.  Without the inhibit option, the filesystem ignores the
disk between the time you press return and the time the format program
ends.  The actual formatting of the disk is identical.  The INHIBIT option
is there (I think) to allow disks so corrupt that they crash the filesystem
to be reformatted. I also remember hearing that it is there for compatibility
with when WB calls the formatter. The difference between the described after-
crash behaviors is due to the following:
  write file
		<--- corrupting crash
  write file header
		<--- another corrupting crash
  write directory block
		<--- a crash the validator can automatically recover from
  write free-block bitmaps
		<--- a crash the validator can automatically recover from
  mark bitmap as valid in root block
       
It all depends on whether the crash occured when the disk was in a contradic-
tory state or not. If only the bitmap is bad then the validator will
recreate it by examining all files on the disk.  If there is an inconsistancy
at this time (like two files using the same block, resulting in a
"duplicate key" error) then the validator will tell the filesystem that
the disk is invalid and the filesystem will mark it as readonly, allowing
you to copy the files that are good off the disk before reformatting
(or before running DiskDoctor or DiskSalv or whatever).  Good luck!
		-- Darren