From: terry@cs.weber.edu (A Wizard of Earth C)
Subject: Re: Moving Data off a Plexus P6
Keywords: plexus sco data tape drive cpio kermit
Organization: Weber State University  (Ogden, UT)
Date: Fri, 11 Sep 92 02:13:12 GMT

In article <1992Sep10.164018.6497@crd.ge.com> davidsen@crd.ge.com (bill davidsen) writes:
>In article <1992Sep09.192239.13386@openage.openage.com>, paul@openage.openage.com (Paul Fischer) writes:
>| Hi All,
>| 
>| I have a customer with a Plexus P6.  They are moving their Unify database 
>| application  to a SCO server next week, and I am hoping to use their tape
>| drive to cpio the data.  I made a cpio tape on their drive, and read it back
>| in to test the tape.  I came back to my SCO system, and I am able to recognise
>| the tape, but I get "I/O error on read()." when I try to access the data.
>
>  Many machines use various minor device numbers for other tape formats,
>like Xenix ct0 and ct2 (Qic-11, if I remember), or Sun rst0 and rst8. If
>you are lucky some combination of these might help. I don't think SCO
>has ct2 on UNIX, but the minor device number was 16 if you feel brave
>about looking for undocumented features in the driver. Of course if you
>have the drive on SCSI you have a whole new driver.

Many machines support *one* tape format (QIC-11 or QIC 24 only).  150Meg
drives generally support reading but not writing lower densities.

You should try QIC-11, as the standard jumpering on SCO calls for QIC-24.
If you have an Archive controller (or a Computone, which is an OEM'ed
Archive), you can read either QIC-11 or QIC-24 by changing a jumper setting
(open vs. closed).  I have operated a Computone controller and tape drive
with a toggle switch on the back of the case (MUST SET BEFORE POWER ON
FOR ROM INITIALIZATION!) to select between 11/24 for over 4 years with no
ill effect. Check your controller manual for the correct setting.  On the
Computone/Archive, its a vertical (up-down) jumper in the middle of the
board, slightly colser to the top than the bottom.

When going to something with an older driver, it's a good idea to pipe it
through dd with a conv=sync option (for instance, writing a tape on an SCO
system to be read on an NCR Tower/32 or Tower/XP, or Arete 1100, etc.).

You may also see "Out of phase, get help".  If you do, use conv=swab.  If
you need both swab and sync, the syntax is conv="swab,sync".

swab does byte swapping, sync guarantees that a full block is written to
the tape.  Some stupid drives/controllers/drivers have a hard time reading
a partial block.  Instead of returning x<blocksize characters, they return
EOF, and you will lose partial blocks.  Unisys boxes based on the NCR or
Arete boxes will have this problem as well.


					Terry Lambert
					terry_lambert@gateway.novell.com
					terry@icarus.weber.edu
---
Any opinions in this posting are my own and not those of my present
or previous employers.
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