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From: chris@mddc.UUCP (Chris Maloney)
Newsgroups: net.bugs.4bsd
Subject: UDA50 driver and bad blocks
Message-ID: <322@mddc.UUCP>
Date: Wed, 2-May-84 11:36:57 EDT
Article-I.D.: mddc.322
Posted: Wed May  2 11:36:57 1984
Date-Received: Fri, 4-May-84 02:35:51 EDT
Organization: MDDC, Cincinnati, Ohio
Lines: 32

Can some one explain how bad blocks are(should) handled on
the UDA50 disks by the 4.2 driver?   Is the bad block handling
really done by the disk and controller?  What must the driver
do?  What does the comment in the 4.2 driver mean where
under the TODO list is listed "bad-block forwarding"?
We've been running 8 UDA based systems without any trouble
until recently.  One of these disk now gets a bad block in
the same location all the time.  I'm going to reformat and
see what happens.

Is this correct?  My on theroy.
    Once the bad block has been re-mapped the disk/controller
    ensures than when the bad block is read/written it is
    really re-mapped without the driver having to worry.
    What is missing from the 4.2 driver is the code that
    reckonizes a new bad block and requests the disk/controller
    to re-map this block.

Please respond with a follow up if you know as I'm sure
a lot of people are using these disks without knowing what
is really going on.

Thanks,

Chris Maloney
Management Decisions Development Corp.
7209 Dixie Highway
Fairfield, Ohio   45014
(513)874-6464

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