ISC 3.2/harddisk & floppy problems

[Jim Deitch]

In article <113 at odiehh.hanse.de> marzusch at odiehh.hanse.de writes:
>
>   This is a summary of a discussion regarding certain floppy and harddisk 
>   problems under ISC UNIX (2.0.2 and 2.2.1). This topic has recently been 
>   discussed in a local german newsgroup. Since nobody came up with a solution 
>   to this problem I'm summarizing and repeating it here:
>
>
>Due to additional hints and experiences from gemini at geminix.in-berlin.de 
>(Uwe Doering) and tik at abqhh.hanse.de (Michael Havemester) I found two problems
>with ISC's harddisk and floppy drivers (possibly not related to each other):
>
>2nd problem:
>     If you connect two (!) hard disk drives to one (ore even two) `standard'
>     AT type hard disk controller (i.e. MFM, RLL or ESDI drives) you may
>     experience a `hanging' disk controller (making any further disk accesses
>     impossible which possibly destroys one or more file systems) when both 
>     disks are accessed concurrently (to reproduce this problem try to enable 
>     an additional swap partition on the second volume, this will cause lots 
>     of disk accesses on both disks when the system starts paging or swapping).
>
>There seem to be no solutions to these problems, just some workarounds:
>
>workarounds for 2nd problem:
>   a) connect only *one* disk to your system
>   b) throw away your `standard' disk controller (and the disks connected to
>      it) and get a SCSI controller and SCSI disk [a good decision anyway, but
>      quite expensive if you already have two other disks ...]
>   c) try another motherboard ...
>

I must have someone watching over me then.  For the last year I have
been running a system with 2 mfm controllers with 2 drives each and
haven't had any of the problems you describe show up.  Both
controllers are WD1006, 1 with floppy (MM2) and 1 without (MM1).  In
the last 6 months I moved over to a bigger system.  I now have 1 ESDI
(WD1007-SV2), 1 MFM (WD1006-mm1), and an Adaptec 1542A in the system.
All 3 controllers have 2 drives, with the adaptec also having a tape
drive.  Still no problem.  I run Cnews on the system and have the
spool and bin directories on different drives on the same controller
(MFM) and haven't had any problems.  I have 2 swap areas defined, ESDI
drive 1 and 2, and haven't had a problem.  What type controllers and
motherboard are you using?

Jim
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