Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!cwjcc!tut.cis.ohio-state.edu!rutgers!att!lzaz!hcj
From: hcj@lzaz.ATT.COM (HC Johnson)
Newsgroups: comp.os.minix
Subject: Re: Megafile 60 problems, again.
Summary: here is how it can screw up
Message-ID: <454@lzaz.ATT.COM>
Date: 2 Mar 89 17:45:54 GMT
References: <10013@louie.udel.EDU>
Organization: AT&T ISL Lincroft NJ USA
Lines: 36

In article <10013@louie.udel.EDU>, PRINS%HLERUL5.BITNET@cunyvm.cuny.edu (Ryko Prins, CRI, Leiden, Netherlands) writes:
> I am still trying very hard to get Minix working on my Megafile 60, but Minix
> still fights back v e r y effectively.
> If I afterwards try to reboot my ST that often fails because Minix has filled
> some sectors of partition C: (partition 1) and has a definite preference for
> (main) directory sectors.
> 
> Does anyone has an explanation how Minix can destroy data on a partition it
> should stay off?

When MINIX boots the first thing wini_task does is READ sector 0 of the hard 
disk and fill in the local partition table. All hd3 means is use the numbers
in stored for partition 3.  If the read is not working right you are not
getting an error, but are not getting good data either.  The result is bad
numbers indicating where the partition should be. Several suggestions:
1. consider what is printed for the partitions.

2. using a floopy based minix, do od -x /dev/rhd0 and see if the boot
   sector looks reasonable.  There should be 4 partitions near the end.
((pick up the posting of tofile, it includes partition dumps in the docs))

3. Assuming that you did not just screw up the partitioning of hd3 in your
formatter, it souds as if the wini driver is not getting all the SCSI info
out to the megafile correctly.  Some SUPRA users have commented on this
previously.  I know that stwini is not talking to the disk the same way
that I do to my cartridge tape.  

4. a test.  Can you populate a TOS filesystem in partition 3 (drive E:)
   and not screw up C: ??  if yes, it sounds like a driver problem in minix.

5. Remember, a TOS driver polls everything, a Minix driver uses interrupts also.

Howard C. Johnson
ATT Bell Labs
att!lzaz!hcj
hcj@lzaz.att.com