From owner-freebsd-questions  Wed Jan 29 20:14:46 1997
Return-Path: <owner-questions>
Received: (from root@localhost)
          by freefall.freebsd.org (8.8.5/8.8.5) id UAA17863
          for questions-outgoing; Wed, 29 Jan 1997 20:14:46 -0800 (PST)
Received: from gdi.uoregon.edu (gdi.uoregon.edu [128.223.170.30])
          by freefall.freebsd.org (8.8.5/8.8.5) with ESMTP id UAA17844
          for <freebsd-questions@FreeBSD.ORG>; Wed, 29 Jan 1997 20:14:36 -0800 (PST)
Received: from localhost (dwhite@localhost) by gdi.uoregon.edu (8.8.4/8.6.12) with SMTP id UAA27409; Wed, 29 Jan 1997 20:14:25 -0800 (PST)
Date: Wed, 29 Jan 1997 20:14:25 -0800 (PST)
From: Doug White <dwhite@gdi.uoregon.edu>
X-Sender: dwhite@localhost
Reply-To: Doug White <dwhite@resnet.uoregon.edu>
To: Robert Chalmers <robert@nanguo.chalmers.com.au>
cc: bsd <freebsd-questions@FreeBSD.ORG>
Subject: Re: tape dumping speed anomolies
In-Reply-To: <199701292311.JAA01901@nanguo.chalmers.com.au>
Message-ID: <Pine.BSI.3.94.970129201209.25390h-100000@localhost>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
Sender: owner-questions@FreeBSD.ORG
X-Loop: FreeBSD.org
Precedence: bulk

On Thu, 30 Jan 1997, Robert Chalmers wrote:

> I notice that using rdump from the pentium, to the 486 where the tape is,
> I get throughput of 95KBytes/Sec. Yet on the 486 itself, the throughput
> is a miserable 20 KBytes/Sec. The result is of course that the rdump
> from the pentium Streams in to the tape, fast. No hesitation on the part
> of the tape at all. On the 486, the tape shoe-shines away for literally 
> hours and HOURS.

This will happen if the blocksize is wrong.  Try increasing your
blocksize.

And letting it shoeshine isn't too great for the drive.

> I think the soultion will be to run up a 586-100 and put the tape in that,and
> rdump all systems to it?

That may work, but again it does depend on the block size.  This was the
solution with our Connor 4GB; we upped the blocksize to 10K and dump
streams along only stopping to move the head.

> Just coincidentally, The Archive Viper-150MB tape actually dumps and 
> restores to 525MB tapes, and 250's for that matter just fine. Interesting.

This thing uses the huge DC2000 tapes, right?  I think we had one in our
server box until it was replaced with a newer, off-name brand.  Buzzes
right along though :)

Doug White                              | University of Oregon  
Internet:  dwhite@resnet.uoregon.edu    | Residence Networking Assistant
http://gladstone.uoregon.edu/~dwhite    | Computer Science Major