Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!tut.cis.ohio-state.edu!zaphod.mps.ohio-state.edu!wuarchive!texbell!nuchat!steve
From: steve@nuchat.UUCP (Steve Nuchia)
Newsgroups: comp.periphs.scsi
Subject: Re: WrenV 94181-702
Message-ID: <21617@nuchat.UUCP>
Date: 9 Apr 90 06:55:58 GMT
References: <1990Apr6.041431.21725@eng.umd.edu> <7820@quick.COM>
Reply-To: steve@nuchat.UUCP (Steve Nuchia)
Organization: Houston Public Access
Lines: 34

In article <7820@quick.COM> srg@quick.COM (Spencer Garrett) writes:
>The number of sectors per track on a Wren V (94181-702) is not
>constant.  There are more sectors on outer tracks than inner tracks.
>The Berkeley Fast File System insists upon a figure for SPT,
>and is only prepared for a single constant.  The best way to
>deal with this problem, IMHO, is to lie to the partitioning


If you want absolute best performance and don't mind (or maybe
even want) having the drive partitioned, the best way to handle
this is to tell mkfs the truth, which requires having partitions
starting at or near the points where the SPT steps occur.

For that to work you have to know where that happens and
compute a set of head/cyl/spt figures from which you
can back out fake cylinder numbers to feed to the partitioning
software.  Then tell mkfs the real info for each partition.

Even that may be pointless if the embedded controller deals
with errors by slipping all subsequent sectors.  By the time
you get to the middle of the disk your cylinder boundaries
are hopelessly scrambled.  I noticed that Adaptec's ST-506
slave controller has an option to reserve a number of sectors
per cylinder, so the cylinder allignment won't be disturbed
for more than a cylinder or two.  This beats the SMD method
of slipping one sector per track.  Anybody know if any embedded
scsi drives handle errors this way?

-- 
Steve Nuchia	      South Coast Computing Services      (713) 964-2462
"The study of the art of motorcycle maintenance is really a miniature study
of the art of rationality itself.  Working on a motorcycle, working well,
caring, is to become part of a process, to achieve an inner peace of mind.
The motorcycle is primarily a mental phenomenon."  -- Robert M. Pirsig