Path: utzoo!utgpu!jarvis.csri.toronto.edu!clyde.concordia.ca!rutgers!mit-eddie!uw-beaver!zephyr.ens.tek.com!orca.wv.tek.com!pogo!bluneski
From: bluneski@pogo.WV.TEK.COM (Bob Luneski)
Newsgroups: comp.sys.atari.st
Subject: Re: 16 meg partition limit
Message-ID: <8503@pogo.WV.TEK.COM>
Date: 7 Feb 90 01:00:32 GMT
Reply-To: bluneski@pogo.WV.TEK.COM (Bob Luneski)
Organization: Tektronix, Inc., Wilsonville,  OR.
Lines: 40



apratt@atari.UUCP (Allan Pratt) writes in response:

>Also right.  Here's the bottom line: when you have a partition larger
>than 16MB, the driver creates the partition with 1KB sectors (or more!)
>rather than 512-byte sectors, which is the old value.  Cluster size is
>still two sectors, whatever size that is.  The disk itself is formatted
>with 512-byte sectors, and Rwabs does blocking and deblocking, turning
>requests for "one logical sector" into as many physical sectors as
>necessary.

<stuff deleted>

>The moral is, utilities should always use Getbpb to find out how big
>sectors are, how many sectors per cluster, etc., and base all your
>other calculations and "constants" on the answers.  If you're adding
>GEMDOS buffers or other permanent objects, get the release notes and do
>it right.

<<<<<<<<<<<<<<<<<<<<<<<<<<<<<<  WARNING  >>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>>

Under TOS 1.0,1.2, and 1.4 repeated use of Getbpb or Dfree will bring your 
system crashing to a halt! The number of calls until failure depends on your 
system memory utilization but averages in the 35-65 call range.  This 
little bug(feature) was discovered at great loss of time, sleep, and hair
(with a number of forehead bruises also).  The real moral of the story is 
never let someone else do what you can do yourself.  Read in the boot sector 
and pull the sector size off there!  

I strongly agree with Alan that it is the developers responsibility to query 
the system and never to take anything for granted.

****************************************************************************
*  Bob Luneski                                                             *
*  Diamond Back Support Hotline:  bluneski@pogo.WV.TEK.COM                 *
*                                                                          *
*  The opinions expressed herein are my own and in no way reflect the      *
*  opinions of Tektronix, Inc.                                             *
****************************************************************************