[comp.sys.sun] Tape drive vs. interface

fred@rutgers.edu (Fred Barber) (02/04/90)

I have a Kennedy 9300F (125 ips, 800/1600, Pertec [?] formatted) drive
connected to a Xylogics 472 interface in a Sun 3/280 running SunOS 4.0.1.
The drive and I go back a long way.  The Sun and 472 were new about a year
ago.

The drive and interface didn't work at all well together as originally
installed.  I was encouraged by Shugart (who purchased Kennedy somewhere
along the line and don't seem to be TOO keenly interested in THEIR older
products) to upgrade the formatter to current specs, which I did.
Meanwhile, I was encouraged by Xylogics to install special, non-standard
firmware in the 472, which I also did.

Meantime, while all the parts were spread out over the country, we did the
OS installation by hand.  (The install scripts didn't have a prayer of
working, given the severity of the magtape problems.)

Now it's all back together and the NEW OS is here, necessitating a second
go-around, and I'd like to tighten up the tape/interface interaction. 

Everything seems to work perfectly in non-interrupt mode.  When the
interrupts come on (that is, when the mini-root or the OS itself is
actually up and running), there tends to be a flurry of anxiety (missed
interrupt, attempting to resync) that dies down after a bit.  Then
everything is fine except that the first file on the tape seems to
disappear.  That is,

-- "mt fsf" at BOT works fine;

-- attempt to read (e.g., "tar t") at BOT fail with unexpected EOF;

-- "mt stat" at BOT causes an unrequested FSF, then works;

-- all operations beyond the first filemark go without a hitch; and,

-- "mt fsf" at BOT followed by a series of "mt bsr" works fine, as
   long as you don't hit BOT.  That is, you can read what you've
   spaced over up to but not including (I presume) the first record on
   the tape. 

Needless to say, that first file had better not contain anything too
important.  And as for the hard-wired offsets in the install script,
forget it!

Does this ring a bell with anyone?  Is there a known fix, or is it known
beyond all doubt that a fix is impossible?  Is there anyone out there who
has this drive and interface operating properly together?

Fred Barber			cognex!fred@ai.mit.edu
Cognex Corporation		Phone: 617-449-6030
15 Crawford Street		Fax: 617-449-4013
Needham, Mass 02194