[fdutils] format_n_write for faster disk-from-image creation?

Julien Plissonneau Duquene jpd at junk.org
Mon Jul 21 14:10:05 CEST 2003


On Sun, Jul 20, 2003 at 09:27:31PM -0400, Charles R. Anderson wrote:

> It seems possible to shorten the time to make e.g. Linux boot
> floppies by combining the formatting and dd'ing from a disk image
> file, using the 82078's Format with Write command.  Has any thought
> been given to implementing this in superformat?  I think it would be
> a neat addition, and would be willing to do this work if I got some
> pointers describing where this would need to hook into the code,
> feasibility, etc.

IMO you would have to implement this in another utility than
superformat, which is meant to be portable, and uses "standard" Linux
ioctls to format and verify tracks. For example, the "format and
write" capability may not be available on all controllers (like cheap
USB chips).

Anyway to do that you would have to use FDRAWCMD (or implement another
ioctl in the floppy driver), and while you are at it there are other
things to do :
 - verifying while being on the same track (faster) and using raw cmds
   (avoids read-ahead, track changes, retries on errors, *way* faster)
 - write patterns & verify before writing+verifying actual data, also
   using raw cmds, and optionnaly immediately discarding bad disks.

-- 
Julien Plissonneau Duquène.
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