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From: jms@tardis.Tymnet.COM (Joe Smith)
Newsgroups: comp.sys.amiga,comp.sys.amiga.tech
Subject: Re: SEAGATE ST 157N problem
Message-ID: <541@tardis.Tymnet.COM>
Date: 27 Aug 89 08:32:37 GMT
References: <1280@syma.sussex.ac.uk>
Reply-To: jms@tardis.Tymnet.COM (Joe Smith)
Organization: McDonnell Douglas Field Service Co, San Jose CA
Lines: 65
Keywords: HD,SEAGATE,PROBLEM,ARGHHHH

In article <1280@syma.sussex.ac.uk> markf@syma.sussex.ac.uk (Mark Foster) writes:
>I am trying to get my ST 157N to format but it wont go past cylinder 557
>It is supposed to be 615 cyls 26 sec/trk and 6 heads.
>Can someone confirm that this is correct or maybe offer a little advice
>as to what I may be doing wrong.

The ST157N I got came with a printed copy of the test results dated
11/14/88.  It said that my particular drive had only 94860 blocks.
(Previously, Seagate had specified 95015 blocks for the ST157N).
Since 6*26*608=94848 and 6*26*609=95004, it looks like a large hunk
of the 609th cylinder is reserved for bad block replacements.

I decided to make DH0 smaller than 880K so it's entire contents could
be copied to a backup floppy.  I chose its size to end on a block number
that is a multiple of 6*26 and is a multiple of 2*11.  That way I could
have a virtual floppy starting on cylinder boundaries.

For the remainder of the disk, I chose numbers that would leave the
smallest number of unused blocks.

/* OverDrive Drive definition */
/* SEAGATE ST157N with 94860 blocks = 48,456,320 bytes. */

/* RES = blocks    0-  155 = cylinder 0 for boot block and disk label.    */
/* DH0 = blocks  156- 1715 = 780K OFS boot disk on cylinders 1-10.        */
/* DF4 = blocks 1716- 3475 = 1760 blocks for an 880K virtual floppy.      */
/* DH1 = blocks 3476-94820 = 45M FFS partition with 44 blocks per "cyl".  */

DH0:   Device = overdrive.device
   Unit = 1			/* Unit 1 = SCSI drive #0, name MUST be DH0: */
   Flags = 9 ; Surfaces = 6 ; BlocksPerTrack = 26 ; Reserved = 2
   LowCyl = 1  ;  HighCyl = 10   /* The boot block MUST match these values */
   Interleave = 0 ; Buffers = 32 ; BufMemType = 1 ; Stacksize = 4000
   DosType = 0x444F5300   /* Current boot block requires an OFS partition */
   Mount = 1
#

/* DF4 starts at ST157N cylinder 11 = block 1716 = floppy cylinder 78 */
/* DF4 ends at block 3475 = floppy cylinder 157 = ST157N cylinder 22.28 */

DF4:   Device = overdrive.device
   Unit = 1		 			/* emulate a floppy here */
   Flags = 9 ; Surfaces = 2 ; BlocksPerTrack = 11 ; Reserved = 2
   LowCyl = 78  ;  HighCyl = 157			/* 80 cylinders */
   Interleave = 0 ; Buffers = 5 ; BufMemType = 1 ; Stacksize = 4000
#

/* RES+DH0+DF4 = 11 * 6 * 26 + 80 * 2 * 11 = 3476 blocks = 4 * 11 * 79. */
/* 94860 = (4 * 11 * 2155) + 40.  Therefore by pretending there are 44  */
/* blocks per cylinder, all but 40 blocks can be accessed and there are */
/* no wasted blocks between DF4 and DH1.                                */

DH1:   Device = overdrive.device
   Unit = 1				/* 45 megabyte FFS partition */
   Flags = 9 ; Surfaces = 4 ; BlocksPerTrack = 11 ; Reserved = 2
   LowCyl = 79  ;  HighCyl = 2154   /* blocks 3476 thru 94819 */
   Interleave = 0 ; Buffers = 32 ; BufMemType = 1 ; Stacksize = 4000
   DosType = 0x444F5301 ; FileSystem = L:FastFileSystem
   GlobVec = -1 ; Mount = 1
#
-- 
Joe Smith (408)922-6220 | SMTP: JMS@F74.TYMNET.COM or jms@tymix.tymnet.com
McDonnell Douglas FSCO  | UUCP: ...!{ames,pyramid}!oliveb!tymix!tardis!jms
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