Path: utzoo!utgpu!news-server.csri.toronto.edu!bonnie.concordia.ca!uunet!seismo!dimacs.rutgers.edu!rutgers!cbmvax!carolyn
From: carolyn@cbmvax.commodore.com (Carolyn Scheppner - CATS)
Newsgroups: comp.sys.amiga.programmer
Subject: Re: AmigaDOS 2.0 and external hard drives
Message-ID: <22419@cbmvax.commodore.com>
Date: 13 Jun 91 21:53:20 GMT
References: <1991Jun2.193047.8480@msuinfo.cl.msu.edu> <5bEB02Zw08Nj01@JUTS.ccc.amdahl.com>
Reply-To: carolyn@cbmvax.commodore.com (Carolyn Scheppner - CATS)
Organization: Commodore, West Chester, PA
Lines: 34

In article <5bEB02Zw08Nj01@JUTS.ccc.amdahl.com> rzv30@cccvm.ccc.amdahl.com (Rene' A. Vega) writes:
>Be very careful when configuring your existing external hard drive with the 
>Amiga 3000 HDTools program. The reason you're not allowed to specify a 
>partition beginning at cylinders 0 and 1 is because the configuration program 
                                             ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>uses those first two cylinders to house the partition map. One of the last 
>things it does is WRITE to those cylinders. Fortunately for me, both of my 
>external hard drives had an expendable partition beginning on cylinder 0, and 
>so  it wasn't a disaster that those first two cylinders were overwritten. 


I would just like to note that this use of the initial cylinders is not
an arbitrary choice made by HDTools.

The standard Amiga specification for Rigid Disk Block, which was
developed by Commodore-Amiga in conjunction with a number of
3rd party Amiga hard disk controller manufacturers (I believe
over two years ago), specifies that partitioning information, softloaded
filesystems, bad block maps, and other information be stored in a particular
format in the initial cylinders of the drive.
(see Amiga RKM Libs and Devs, Expansion Library chapter for more info)

This is what makes it possible to move many Amiga harddrives not
only between systems but even between different brands of
controllers that support Rigid Disk Block, and have all of
your partitions come up magically.

-- 
==========================================================================
 Carolyn Scheppner -- Tech. Mgr. CATS - Commodore Amiga Technical Support
 PHONE 215-431-9180 {uunet,rutgers}!cbmvax!carolyn  carolyn@commodore.com

 Pad with zeros for a light, airy program.
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