Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!ames!sun-barr!decwrl!decvax!ima!mirror!frog!jr
From: jr@frog.UUCP (John Richardson)
Newsgroups: comp.unix.i386
Subject: Re: Acceptable Unix Configuration?
Summary: re: why not use modeselect
Message-ID: <1890@frog.UUCP>
Date: 1 Sep 89 16:17:00 GMT
References: <459@telesoft.telesoft.com> <6700019@adaptex>
Organization: Charles River Data Systems, Framingham MA
Lines: 37

In article <6700019@adaptex>, neese@adaptex.UUCP writes:
> 
> Yes, it is the AHA-1542A that has the floppy controller on the adapter.
> I would recommend another choice for hard drives.  My personal preference
> in the 150MB capacity range is the CDC Wren V HH.  Formats to about
> 172MB and has a better transfer rate than the Micropolis and less overhead
> also.  Just make sure you ask if the read ahead buffer is enabled.  By
> default, CDC ships their products with read ahead disabled.  It is only
> controllable via software, but can be set permanently.  There is a 400%
> difference in the performance when read ahead is enabled.  Again, this
> is just my personal preference.
> 
> 
> 			Roy Neese
> 			Adaptec Central Field Applications Engineer
> 			UUCP @ {texbell,killer}!cpe!adaptex!neese
> 				merch!adaptex!neese

   Why not put the mode select in. I have written a SCSI driver that includes
support the the AHA-15xx family controllers, and have target function modules
that can set specific MODSELECT parameters for given drives. I use the
indentify command to find them, and if I do not have a table for one, then
I use defaults.
  The reason I do this is because I need to carefully fiddle the cache
parameters so that the drives disconnect from the SCSI bus whenever a
read can not be satisfied. IE: Waiting for mechanical motion of either the
arm or platter. I am using up to 3 of the AHA-15xx controllers controlling
multiple drives with the data stripped across them. (2 GB of data supported
on 10 drives for a high speed OLTP database product)

Also, is a UNIX 5.3 source of the driver from ADAPTEC available? My driver
is for our OS (UNOS), and I would like to bring over support for the striping
to the System V/386 world.

If the source is not available, I will have to re-write it from scratch.

					JR