[NTLUG:Discuss] Linux boot floppy -- making it without windows ordos

[Burton Strauss]

I doubt it's any major 'flaw' in the driver, probably it's just different
ways of handling failure.

Why is rawrite different from dd?  Two possibilities - one is that there are
differences in what the underlying device driver (Win vs. Linux) reports.
The second is that the two programs themselves have different error handling
coded.

Suppose you write a block and it fails.  You retry and it works...

Is that a GOOD thing?
  YES: You have done what the user asked - written data to a non-volatile
medium
  NO:  You have indications that the medium may not contain the proper data

You retry six times and it finally works... Is THAT a GOOD thing?  20
times??


In a perfect world you would then read-after-write to verify.  Excluding the
cache problem (reading the cached data vs. the actual floppy), if you get
the expected results is that a GOOD thing?

  YES: You have confirmation that the disk is readable (ON THIS ONE
MACHINE/DRIVE) and has the correct contents.
  NO:  Underlying ECC might be hiding a repairable failure from you - fine
until the next bit dies and the error becomes unrepariable.

Etc.



So as a general rule, any floppy which ever reports any problem gets crushed
and trashed.  They're cheap and not worth the risk of data loss, especially
over time.


-----Burton



-----Original Message-----
From: discuss-bounces at ntlug.org [mailto:discuss-bounces at ntlug.org] On Behalf
Of Terry Henderson
Sent: Thursday, January 13, 2005 1:04 AM
To: NTLUG Discussion List
Subject: Re: [NTLUG:Discuss] Linux boot floppy -- making it without windows
ordos

On Wed, 12 Jan 2005 23:07:44 -0600, Peter A. Koren
<p.koren at worldnet.att.net> wrote:
> On Sat, 2005-01-08 at 16:30, Burton Strauss wrote:
> > If you are getting bad blocks when you create boot disks on new, 
> > reasonable quality disks, then the problem is most likely NOT the 
> > disks, but the drive...
> >
> > Try a new Floppy drive.
> >
> > -----Burton
> 
> And the winner is Burton Strauss. Yes, it was the floppy drive itself. 
> I salvaged a drive from an old pc and switched out the defective 
> drive. It all works now as far as I can tell. I will have to wait at 
> least until the weekend to try to install Mandrake 10.1, so I may be a 
> bit premature. But there is no doubt that the old drive was toast.
> 
> But it is interesting that I have in the past always been able to get 
> rawrite to work and never have been able to get dd to work with the 
> bad drive. So I would still say the device driver for floppies under 
> linux, at least for the format used by boot disks, is not as good as 
> what the Windows driver provides.
>
 I think your suppositions are flawed.  I've had little or no trouble with
dd or rawrite either one as long as floppys were good.  I don't think one is
any better than the other.  Not much difference as far as I can tell, they
both work just fine as long as media and hardware is ok.

> Though I have not tried it, I suspect my old Windows 98 boot floppy 
> will now work. But the only reason I wanted Windows at all was to make 
> Linux boot floppies. So no more Windows for me.
> 
> --Pete