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Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!eos!shelby!portia!roadman
From: roadman@portia.Stanford.EDU (arthur walker)
Newsgroups: comp.sys.amiga,comp.sys.amiga.tech
Subject: Re: SEAGATE ST 157N problem
Keywords: HD,SEAGATE,PROBLEM,ARGHHHH
Message-ID: <4833@portia.Stanford.EDU>
Date: 25 Aug 89 16:35:35 GMT
References: <1280@syma.sussex.ac.uk>
Sender: arthur walker <roadman@Portia.stanford.edu>
Followup-To: comp.sys.amiga
Organization: Stanford University
Lines: 39

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 with all SCSI, we don't really know how it's blocked out inside, but
seagate suggests a 6 x 26 x 608 for my 157N, which is just about perfect
for its advertised 94860 blocks available. SCSI INQUIRE does say 6 x 26 
x 608, but there's no guarantee.  94860 is really the important number;
My syquest drive tells me that the cartridges have 1275 cylinders, but 
for some reason its block sparing strategy on format was changed after those
numbers were fixed, and using a 2 x 34 model for surfaces and blocks, I
only get 1270 cylinders out of 86700 blocks.
  
> 
> My mountlist entries are for two partitions DH0: and DH1: with DH0:
> starting at cyl 0 to cyl 38 and DH1: for the rest.
> 
> This type of arrangement works fine for the ST 138N.
> 
> p.s. The system is an A500 with KS 1.2 and an Amdrive SCSI interface.
I don't know this vendor, but it sounds to me as though the DOS format
is what's hanging.  I think one or more sectors of the drive have gone
south since the last low format, and you should re-low-format the drive.
Its firmware will map the offending sector/s out.  

If you know someone with a mac, you can get a lot of info about bad sectors
with SCSI Evaluator.  You can even REASSIGN bad blocks without re-low-format
on drives which support it - and I believe the seagate drives do.  This can
be a life-saver when blocks go bad on a full volume...unless you are really
unlucky, you lose only the data on the sector and if you are clever you lose
the surrounding file at worst.

I say, redo the low-format.  If your vendor's prep software doesn't 
support an atomic format, do it on a friend's machine.  The low format is
host-independent.

art walker
roadman@portia.stanford.edu