Subject: Re: /rescue, crunchgen'ed?
To: Lennart Augustsson <firstname.lastname@example.org>
From: Richard Earnshaw <email@example.com>
Date: 08/30/2002 13:13:58
> tld wrote:
> > Something I wondered and now I'm going to ask:
> > If, as it seems, for some perople the fact that a crunchgen'd binary
> > is less safe because it can be damaged by bad sectors, and you really
> > don't know if it has until it is time to use that.
> > What I suggest is a script executed (say) weekly like `cat
> > /rescue/the_big_file >/dev/null 2> /dev/null || echo "It has bad
> > sectors!"`
> That doesn't really help. I had a disk crash recently that consisted of
> a few scattered
> sectors on the disk suddenly being unreadable. Before this point in
> time everything
> was fine, but suddenly... BOOM. And after that, you had to be very
> careful which
> executables you tried to run. A crunchgened /rescue would probably have
> that I was hosed at that point. But if you have an old machine you
> probably have
> a floppy to boot from at that point.
If your bad sector had been in /bin/sh you'd have been equally hosed. If
you have a probability N of a bad sector on a disk and P sectors of
'critical' code needed for recovery with statically linked executables and
Q sectors of 'critical' code with a crunchgened executable, then the
probabilities of the bad sector lying in your critical code are P*N and
Given that practically everything in /bin and /sbin could be considered
critical for some problem, you are clearly better off if Q < P.