Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!texbell!merch!cpe!adaptex!neese
From: neese@adaptex.UUCP
Newsgroups: comp.sys.ibm.pc
Subject: Re: BACKUP SOFTWARE & SCSI DRIVES
Message-ID: <27800005@adaptex>
Date: 10 Apr 90 21:07:00 GMT
References: <126@fryeten.uucp>
Lines: 32
Nf-ID: #R:fryeten.uucp:126:adaptex:27800005:000:1716
Nf-From: adaptex.UUCP!neese    Apr 10 15:07:00 1990


>/* ---------- "BACKUP SOFTWARE & SCSI DRIVES" ---------- */
>Can someone suggest a backup software package that is comparable to Fastback
>in speed and economy of space that will work with SCSI drives.  Fastback
>doesn't seem to like SCSI drives and their tech support people have confirmed
>this.  It has something to do with the speed of the SCSI drive and DMA.  They
>weren't too specific.

I will **assume** (yes I know what that means), that you might have a AHA-154x
adapter.  Whether you do or not, here is some information regarding the use
of Fastback and the 154xA adapter.  There is a program on adaptex called
SETSCSI.EXE.  It is really intended for the use of backup programs that
use a floppy tape drive.  Some explanations:

1) Fastback will almost always fail the DMA test for the 154xA, because it
doesn't know about the 154xA having its own DMA.  This is no cause for concern.

2) If you are using a floppy tape drive or floppy disk, then you need to use
SETSCSI to adjust the 154xA bus on/off times.  By default the 154xA uses 11
micro-seconds on and 4 off.  During the time the 154xA adapter is on the
bus, nothing else can happen.  The lengthy bus on time causes grief for
software that is running a DMA channel while reading/writing to the hard disk.
Like Fastback does.  Basically, the on-board CPU DMA starves while the 154xA
is on the bus, so...  If you use SETSCSI in a batch file to set the bus on
time to 6 or 7 micro-seconds, then everything will be happy.  This allows
the sytem DMA to run without starvation.

			Roy Neese
			Adaptec Central Field Applications Engineer
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