Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!snorkelwacker!spdcc!ima!minya!jc
From: jc@minya.UUCP (John Chambers)
Newsgroups: comp.unix.wizards
Subject: Re: Panic button SCSI disk reformat! [Summary]
Message-ID: <60@minya.UUCP>
Date: 8 Nov 89 14:43:24 GMT
References: <1989Oct27.222806.28576@genisco.uucp> <1989Nov5.183341.27545@world.std.com>
Organization: home
Lines: 38

> >You can then do something like:
> >
> ># format -d sd0 << XXX
> >format
> >y
> >XXX
> >
> >and format will start crunching away!  (I expected the system to crash,
> >but it didn't!  It even verified the disk, and then let me relabel it.)
> 
> You should add some relatively simple code to unmount it. Otherwise
> buffers being held in memory might be written back which could make
> sensitive data re-appear if that area of the disk has already been
> reformatted.

OK, maybe I'm giving away my non-wizard status, but I can't quite see
how you persuade the kernel (Sys/V or BSD) to umount the root partition.
Is it really "relatively simple"?  If so, how do you do it?

As an alternative, I suppose you could do a sync or three before the
format, to flush out the buffers.  Too bad there doesn't seem to be
a good (portable) way to know that a sync has completed.









[To satisfy the line counter]

-- 
#echo 'Opinions Copyright 1989 by John Chambers; for licensing information contact:'
echo '	John Chambers <{adelie,ima,mit-eddie}!minya!{jc,root}> (617/484-6393)'
echo ''
saying