From: gezelter@rlgsc.com
Newsgroups: comp.sys.dec,comp.unix.ultrix
Subject: Re: Sanitize End Sectors?
Date: 10 Nov 92 15:47:15 GMT
Organization: Robert Gezelter Software Consultant, Flushing, NY

In article <1992Nov9.155043.4580@relay.nswc.navy.mil>, wdence@nswc-wo.nswc.navy.mil (Walter Dence) writes:
> 
>      I need to send some files out.  I need to wipe the ends of the 
> end-sectors with zeros (or circumflexes, or anything).  This is
> in case there is any sensitive info carried over into them from
> a previous disk volume that had sensitive info.
> 
>      There was a similar flap several months ago over Prodigy.
> 
>      Is there a DCL batch file or other utility to do this?
> 
>      Is there a FAQ for this newsgroup?
> 
>      Is there an Internet FTP site for DEC-VAX stuff?
> 
>      Does "High-Water Marking" have anything to do with this?
> If a disk volume is set to "Overwrite-on-delete", will this fix
> this problem.  Does the VAX environment have these features and are
> they commonly used for this?
> 
>      Thanks,
>      Walt Dence
> 
> 
> 
> =====================================================================
>                        WALTER E. DENCE, JR.
>                    Data Acquisition Specialist
>                  Influence Mechanisms Branch, G95
> 
> Commander, Dahlgren Division                        
> Naval Surface Warfare Center     Office:          (301) 394-1707/1960
> Dahlgren Division Detachment     Fax:             (301) 394-4510/4727
> White Oak, G95 (W. Dence)        DSN (AutoVoN):         290-1707/1960
> 10901 New Hampshire Ave.         MilNet: wdence@nswc-wo.nswc.navy.mil
> Silver Spring, MD 20903-5000     Home:                 (301) 229-7394
> 
>          (This is personal opinion, not official opinion.)
> =====================================================================
-- 
Walt,
 
There have been many discussions in a variety of arenas. The 
exact answer depends upon who is doing the asking and who is 
doing the asking. 
 
There are, I believe, some programs in the DECUS library to zero 
blank disk packs completely. In any event, you probably want to 
do this BEFORE the volume is INITIALIZED, not after. Then you 
want to copy the files onto the now freshly scrubbed and initialized volume.
 
The flap over Prodigy was a result of the fact that unlike memory 
contents on VMS, the contents of disk blocks are not, by default, 
zeroed before re-use on DOS (or VMS).
 
You can use the /ERASE switch on DELETE operations to force VMS 
to do at least a simple erase on DELETE, but, if memory serves me 
correctly, the specially designed disk scrubbing programs are 
more thorough (and take significantly longer to run).
 
I hope that the above has been helpful. If I can be of further 
assistance, please feel free to contact me by phone or Email.
 
- Bob
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