Path: utzoo!attcan!utgpu!jarvis.csri.toronto.edu!rutgers!cs.utexas.edu!uunet!bywater!acheron!archet!larouch!jparnas
From: jparnas@larouch.UUCP (Jacob Parnas)
Newsgroups: comp.sys.ibm.pc.rt
Subject: Re: ESDI disks for RT (AOS 4.3)
Summary: Try using 36 sectors/track on disk jumpers and format (sautil)
Message-ID: <325@larouch.UUCP>
Date: 13 Jun 89 00:43:29 GMT
References: <3396@ursa-major.SPDCC.COM> <1269@ibmpa.UUCP>
Reply-To: jparnas@larouch.UUCP (Jacob Parnas)
Organization: Larouch Headquarters, Hopewell Junction, NY
Lines: 35

In article <1269@ibmpa.UUCP> conrad@ibmpa.UUCP (Conrad Minshall) writes:
>In article <3396@ursa-major.SPDCC.COM> dyer@ursa-major.SPDCC.COM (Steve Dyer) writes:
>>It gave a write error on each track (sector=1 SCT=34),
>>and one which didn't disappear with repeated formats, and the drive gave
>>errors trying to run newfs under AOS 4.3.
>
>The EESDI disks for the RT, as shipped by IBM, have a "hidden defect table" at
>the 18th sector on the 2nd track of the 1st cylinder.  See disk(4) man page.
>I suspect your troubles result from the fact that your disks do not have such
>a table on them.  Format(8) uses the presence or absence of such a table to
>decide whether there is a hidden sector at the end of each track.  Ie format
>adjusts its idea of the number of sectors per track if the table is present.
>
>Conrad Minshall uunet!ibmsupt!conrad (415)8554454 conrad@ibmpa.tcspa.ibm.com
>         None of the above represents IBM's Official Policy, etc.



I been able to format raw CDC/Imprimis Wren V disk drives and Priam 638
drives, with all 36 sectors/track used with no problems.  We've done
this on literally dozens of drives and never had that problem.  Try setting
your jumpers/dip switches to use 36 sectors per track and tell format to
use all 36 sectors/track and not use the hidden defect table.  I found that
at least CDC Wren V usually have under a dozen bad sectors on them (often
just 3-6), so it doesn't seem worth using the hidden defect table.  The
few extra seeks shouldn't be noticed, plus you should gain about an extra
10 Megabytes on a 380 MB disk.

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