Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!convex!mic!letni!rwsys!merch!cpe!adaptex!adaptx1!neese
From: neese@adaptx1.UUCP
Newsgroups: comp.periphs.scsi
Subject: Re: Random Access DAT
Message-ID: <283400147@adaptx1>
Date: 16 Jun 91 13:07:24 GMT
References: <4340@newshost.anu.edu.au>
Lines: 28
Nf-ID: #R:newshost.anu.edu.au:4340:adaptx1:283400147:000:1181
Nf-From: adaptx1.UUCP!neese    Jun 15 11:35:00 1991


>/* ---------- "Random Access DAT" ---------- */
>
>1. Now that DAT is available with fairly high speed random access, is
>there any software available to actually USE this? (Or for Exabyte
>which is only slightly slower, or indeed any older software to use
>seeks on a raw character device?)

BEWARE!  The method youare refering to is called QFA (Quick File Access)
and is implemented very differently from manufacturer to manufacturer.  This
was due to the lack of a defination in the SCSI spec when these devices
were designed.  The spec now contains the new commands for this, but it will
be a while before everyone implments them.

>2. Do the drivers normally provided on Unix systems (e.g. ISC 386/ix 2.2)
>allow for random seeks or would new drivers as well as application
>software be needed? (If so, are any such drivers available?).

No, for the reason above.  I wouldn't want to write a tape specific driver that
would not work with a limited number of drives.  I am sure none of the
suppliers of UNIX's would either.

>STUFF DELETED<

			Roy Neese
			Adaptec Senior SCSI Applications Engineer
			UUCP @  neese@adaptex
				uunet!cs.utexas.edu!utacfd!merch!adaptex!neese