*BSD News Article 3987


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Newsgroups: comp.unix.bsd
Path: sserve!manuel!munnari.oz.au!uunet!destroyer!sol.ctr.columbia.edu!news.unomaha.edu!cwis!jsaker
From: jsaker@cwis.unomaha.edu (James R. Saker Jr.)
Subject: Re: 386BSD QIC-02 Driver with Wangtek 5150PK is sloooooow
Message-ID: <jsaker.714361130@cwis>
Sender: news@news.unomaha.edu (UNO Network News Server)
Organization: University of Nebraska at Omaha
References: <1992Aug17.191318.8853@hotb.sub.org> <1992Aug19.051745.16119@zip.eecs.umich.edu>
Date: Fri, 21 Aug 1992 01:38:50 GMT
Lines: 42

dmuntz@dip.eecs.umich.edu (Daniel A Muntz) writes:

>The problem isn't the 512-byte blocks, per se, but that the controller doesn't
>receive data quickly enough to allow the drive to stream properly.  You can
>get some performance improvement by buffering data in the driver and polling
>the controller instead of waiting for interrupts and timeouts.  Perhaps
>someone could comment on why so many interrupts seem to get lost.  I've
>hacked wt.c to do buffering and polling to make the qic-02 drives usable, but
>this isn't really the "right" solution.  A couple of thoughts:

Would this explain why my tar -cvf /dev/rwt0 to my Wangtek QIC-150 drive
produces unusual "features", including:

	o wildcard tarring writes only one file from each sequence,
	  for example, tar -cvf /dev/rwt0 etc*   with files etc01 to etc09,
	  etc10 to etc19, etc20 to etc29  results in one file from etc0*,
	  one file from etc1*, etc. (i.e. etc04, etc18, etc21, etc33 being
	  the only ones written)

	o tarring large files (esp. large tar.Z files) results in an
	  end of tape not found error

	o accessing floppies during tar operation results in errors
	  in the floppy operation

Tar has no problem reading from the unit - even sizable files written
from another system to tape. And the files it does write to tape are
reliable and hold their integrity.

Any ideas/suggestions? While I'm on the podium, how about plans for
EISA support eventually?;-)

>  -Dan


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..  Jamie Saker					jsaker@cwis.unomaha.edu    .
..  Network Costing Analyst			Business/MIS Major	   .
..  Telenational Communications			Univ. Nebraska at Omaha	   .
..  (402) 392-7548							   .
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