From: Brian Decker (reagan!
Date: Thu Dec 03 1992 - 01:48:31 CST

Okay.... here is a summary of my previous summary......

I understand that I can set up the format command to purge only
selected partitions on a disk:

-> Start format and select a disk. Then use "print" from the
-> "partition" menu to find which cylinders correspond to which
-> partitions. Then, from the "analyze" menu, chose "setup". This
-> allows you to chose the parameters format uses. In the following
-> example cylinders 100-500 are selected:
-> analyze> setup
-> Analyze entire disk [yes]? no
-> Enter starting block number [0, 0/0/0]: 100/
-> Enter ending block number [204539, 973/5/34]: 500/
-> Loop continuously [no]?
-> Enter number of passes [2]:
-> Repair defective blocks [yes]? no
-> Stop after first error [no]?
-> Use random bit patterns [no]?
-> Enter number of blocks per transfer [126, 0/3/21]:
-> Verify media after formatting [yes]?
-> Enable extended messages [no]?
-> Restore defect list [yes]?
-> Restore disk label [yes]?
-> You can then select "write", "compare" or "purge" depending on
-> your level of paranoia.

Many humble apologies for *not* mentioning this earlier.

After careful consideration with my customer, it appears that triple-pass
overwriting of the partitions in question will be satisfactory. Laura Pearlman
of RAND Corp. provided source for a "scrub" program that does just that.

Although *UniShred*, from Los Altos Technologies appears to be accredited,
I definitely will verify their advertising before using *UniShred*.

However, all of this depends on individual sponsoring organization requirements.

PS: Too many replies to acknowledge individually, but special thanks to
      John Marsh (
      Laura Pearlman (
      Ray Smith (rcsmith@analytics.ccom)
      Carl Brown (

< OO >

========================== Previous Summary Follows =========================
>> OK, here is a LATE summary. Regarding the following:
>> Hello;
>> I am currently involved in the construction of a Sun-based information
>> system. One of my requirements is to be able to purge all data from several
>> SCSI disk partitions upon request. I looked into the format->purge->analyze
>> option provided with SunOS, but it appears that that particular command can
>> only be used to affect entire disks, not single partitions.
>> Do you (collectively) know where I might obtain some utility (preferably
>> in source form) that can purge selected disk partitions ??
>> Thanks for the assistance!
>I received many, many replies that pointed out a possible solution using
>dd if=/dev/zero of=/dev/rsd<your-partition-here> (thanks
>( Should have thought of this first, but... )
>However, my customer for this project has "high security data security
>requirements" ( and I require a solution that is
>approved by NCSC. Ray Smith ( pointed out that Los Altos
>Technologies ( has a product, *UniShred*, available to do what I
>need. Their advertising blurb (if you belive it) indicates that they are
>approved for use by the NCSC, NSA, etc, etc, .....
>Sooooooo, unless someone knows of a freely available source form utility that
>is approved by the various 3 and 4-letter agencies, I think that my solution
>is *UniShred*.
>Thanks to all who answered, especially those who inferred my security
>requirements from my generic question, and to all a good night!

"I am not a number, I am a FREE MAN!" - The Prisoner
+ Brian D. Decker + INTERNET: arthur! +
+ E-Systems, Ashburn, VA, USA + VOICE: (703) 729-6000 x3658 +

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