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From: JOHNC%CAD2.DECnet@GE-CRD.ARPA.UUCP
Newsgroups: mod.computers.vax
Subject: Bad Block Files
Message-ID: <8702191240.AA20498@ucbvax.Berkeley.EDU>
Date: Wed, 18-Feb-87 17:16:00 EST
Article-I.D.: ucbvax.8702191240.AA20498
Posted: Wed Feb 18 17:16:00 1987
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Kevin Oberman writes in response to ANK's question on bad block files:

>>There comes a time when all of us are forced to use old disks, or
>>disks that have something that one does'nt need. So, we had an
>>unfortunate crash, and a new DRA0: or SYS$SYSTEM disk had to be made
>>from a backup. 
>
>It's not the lack of BADBLK.SYS that is bothering you. BADBLK.SYS is a
>VMS file and is never on a disk until after initialization. What is
>missing is the Manufacturer's Bad Block information which is (was?)
>written on the last track of the disk when the manufacturer checked
>the media prior to shipping. This information is also missing from
>many and perhaps all disks purchased form third parties. 
>
>While the information that may have been in this area is lost forever,
>I believe that this area may be recreated by one of the diagnostics.
>Either EVRAA or EVRAC. I think the required section is PACKINIT. If
>you lack DEC diagnostics, many third party disk vendors supply code to
>perform this function with their systems. I know SI does. 

This is the sequence I have used on a DEC RP06 disk when it got it's MDBBF
(Manufacturer's Detected Bad Block File) creamed.  

	$ set def [sysmaint]
	$ run essaa
      ds> att rh780 sbi rh0 8 5		! note:  this must describe your
      ds> att rp06 sh0 dba0		! disk.  Field service should be
					! able to help.  This says "There's
! a massbus on the SBI at nexus 8, and an RP06 that's called dba0 at 
! unit 0 on the massbus

      ds> sel dba0
      ds> run evrac/sec:packinit
            .... Program

 	Testing:_dba0:

	DISK TYPE =
	PACK STRUCTURE =               PACK LABEL=  <label>
	PACK IS NOT LABELED SCRATCH

		******* WARNING ********

	Do you wish to continue?  Y

 	CTRL C after format has finished
	
     ds> SUMMARY

     ds> CTRL Y

	$ mcr bad				! now you can run BAD
     bad> dba0:/list
     bad> ctrl Y

        $ init dba0: <label>			! and init the disk


Good Luck!  

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