Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!mailrus!cs.utexas.edu!uunet!cbmvax!andy
From: andy@cbmvax.UUCP (Andy Finkel)
Newsgroups: comp.sys.amiga
Subject: Re: Hard Disk Driver Help Wanted
Message-ID: <8590@cbmvax.UUCP>
Date: 16 Nov 89 17:09:13 GMT
References: <40676@wlbr.IMSD.CONTEL.COM>
Reply-To: andy@cbmvax.UUCP (Andy Finkel)
Organization: Commodore Technology, West Chester, PA
Lines: 44

In article <40676@wlbr.IMSD.CONTEL.COM> steve@mickey.imsd.contel.com (Steve Childress) writes:
>Need help with Amiga DOS Disk Driver ....
>Along comes 1.3.
>
>When I user 1.3's FORMAT for FFS, I note that it calls the driver to 
>format each track, then reads that track. The 1.1 and 1.2 formatters
>did that too. However, when that "verify" CMD_READ yields an error
>due to a flawed sector, my driver returns an error, as usual. The
>formatter then aborts, saying "BAD DISK, TRY ANOTHER"!!!
>
>Am I missing something? Isn't the formatter supposed to recover from
>these read errors by marking that block as USED in the sector allocation
>map, or some such strategy? (It doesn't seem to matter WHICH sector is bad.)

Nope; our model has been that the driver hides the details of
bad blocks from the filesystem.  The filesystem has no bad block
remapping logic.  In 2090 and A590/A2091 drivers, the bad block
logic is in the drivers.  (Note that in a SCSI only driver, the
bad block logic can become fairly simple, since many SCSI drives
support a 'Remap Block' command).

The Format program is an AmigaDOS
filesystem format program; it expects the driver to hide bad
blocks from it;  Until 1.3 you could format a pizza and not have it
notice errors.

>Do I *HAVE* to have a DISK PREP program which does a low level format
>prior to running CBM's FORMAT program? I didn't in 1.1 and 1.2.

No; but your driver has to handle the low level bad block mapping.

If your driver doesn't support bad block mapping, and its a preformatted
drive, you might as well just format QUICK.  Only if the root block
and the boot block are bad will format complain.  But you are
playing a game of chance.  Sooner or later you'll get a grown defect
on the drive.
-- 
andy finkel		{uunet|rutgers|amiga}!cbmvax!andy
Commodore-Amiga, Inc.

"It's impossible to multitask in less than 4 meg."

Any expressed opinions are mine; but feel free to share.
I disclaim all responsibilities, all shapes, all sizes, all colors.