ADSM-L

Re: Drivers for 3590's

1996-12-05 13:03:09
Subject: Re: Drivers for 3590's
From: Richard Sims <rbs AT BU DOT EDU>
Date: Thu, 5 Dec 1996 13:03:09 -0500
Craig Bell, of ADSM Server Development said:

>So if you hear that ADSM is not using the capabilities of 3590, DON'T BELIEVE 
>IT!

Back on July 10th I submitted to the list, describing my experience of
attempting to restore 10GB of avg 1MB files from one 3590 tape, which
took over 46 hours.  In response, David Bohm of ADSM technical support
said:

>It is true that ADSM does not make the best use of the 3590 capabilities
>as Chris suggests.  ADSM treats the tape as sequential media and does
>not account for the multiple track serpentine type recording of this
>tape device.  There is a requirement that has been answered as suggestion.
>Your local IBM marketing rep can add you to request R056215 in the HONE
>data base.

I obtained a copy of the HONE item, and it does describe ADSM failing to
account for the serpentine technology of the 3590, corroborating what
David Bohm said.  Specifically, when ADSM goes to access files on the tape
it processes the tape sequentially, not knowing that by switching tracks it
could access the files much faster, in a more random manner.  The crux of
the problem is that ADSM records file location information only to the point
of knowing what tape the file is on.  The optimal solution, as outlined in the
HONE item, is to additionally track where each file is on the tape, in the
ADSM database.

Craig, we greatly appreciate your response, given the great silence that we
have had over the history of this problem, which is a very sore point with
so many customers who had been marketed the great performance gains to be had
by investing in 3590 technology.  But your response makes it sound like there
is no problem with ADSM's handling of 3590, which doesn't agree with either
experience or other IBM sources.  Obviously, more clarification is needed.
And we need the long-sought improvements in ADSM's use of the 3590.  We would
appreciate hearing substantive information about how work is progressing
toward realizing this goal, and when such an improved server would be available.

      Richard Sims, Boston University Office of Information Technology
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