[COLUG] FreeBSD Mystery

[Balint, Jess]

You shouldn't have to use dd, but just reformat the partition in question.

> -----Original Message-----
> From: Dave Maxwell [mailto:emaxwell at columbus.rr.com]
> Sent: Thursday, June 26, 2003 6:33 PM
> To: colug at colug.net
> Subject: Re: [COLUG] FreeBSD Mystery
> 
> 
> On Thursday 26 June 2003 03:01 pm, Victor Smith wrote:
> > To jump right into it:
> >   I have been learning FreeBSD, therefore installing it 
> with different
> > configurations on a dual 400 box with the 5.1 RELEASE using 
> UFS2 on a
> > 15GB 75GXP HDD.
> >   My problem occurs when I do a fresh install the files 
> from the last
> > time are still there and intact. I have even installed Windows on it
> > then removing that and putting FreeBSD back on, just to find those
> > files are still there. The files include a soft link to /usr/home,
> > source tree and some of /etc among other things. The only thing that
> > works is using IBM's DFT and erasing the disk.
> >   Why is this happening? Does UFS2 maintain a catalog that cannot be
> > deleted using and form of fdisk?
>  
> That happened to me a few years ago with the then current 
> reiserfs.  In my 
> case it was a happy accident because the filesystem was 
> fubared and I only 
> wanted the disk back.  Being able to read the files again was 
> a bonus.  If I 
> had to guess what causes it, I would say the filesystem installs onto 
> partitions in a nonstandard way.  
> 
> Fdisk (most any variety) only overwrites control structures 
> in a partition 
> table.  Much like rm doesn't erase files but only unlinks 
> them, fdisk only 
> creates partition tables that say the partition is free.   
> You have to do a 
> so-called low-level format to truly erase the disk.  
> 
> Anybody else have a better idea why this sometimes happens?
> 
> If all else fails try something like this (I'll have to use 
> the Linux names 
> for devices just put in what FreeBSD calls them):
> 
> #dd if=/dev/zero of=/dev/hda
> 
> And then partition and reformat the drive.  One variation if 
> you want to make 
> fairly sure nobody can ever recover anything would be:
> 
> #!/bin/bash
> 
> x=0
> 
> while [ "$x" -lt 8 ]
> do
> dd if=/dev/random of=/dev/hda
> x=`expr $x + 1`
> done
> 
> exit 0
> 
> That will overwrite the device 8 times with random bytes. I'm 
> using a Linuxism 
> again so you'd have to use FreeBSD's equivalent to /dev/random or 
> pseudorandom generator of some sort. Come to think of it, if 
> I was that 
> worried I would just drill through the platters a bunch of 
> times and take a 
> blowtorch to whats left.
> 
> Dave
> 
> -- 
> The computing field is always in need of new cliches.
> 		-- Alan Perlis
> 
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