You are still limited to a maximum linear VSAM file size of about 4GB.  You
cannot define a single large dataset to used up the entire mod-27 like you
can on an AIX system.

-----Original Message-----
From: Sam Sheppard [mailto:SHS AT SDDPC.SANNET DOT GOV]
Sent: Thursday, July 10, 2003 2:32 PM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: TSM and mod-27 devices


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>>--> 07-10-03  14:25  S.SHEPPARD     (SHS)    TSM and mod-27 devices

Well, I'll take a stab at this.  We just converted from an old RVA to
an ESS-800 and wondered the same thing.  General agreement seemed to be
there weren't really any advantages to mod-27 unless you're running out
of addresses and there were some downsides, mainly the inability to
start more than one I/O to the device at a time without PAV. I'm not
really sure what kind of problems you might see, performancewise. Might
be OK.  There is also the size limitations on the log/db which would
prevent you from using the entire 25GB with one dataset.

There are probably other considerations, but we had no reason not to
just stick to lots of mod-3s.

I know I asked the same thing here about a month ago and didn't get
much feedback.  Anyone else tried this?

Sam Sheppard
San Diego Data Processing Corp.
(858)-581-9668
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>>--> 07-10-03  07:46  ..NETMAIL     ()     TSM and mod-27 devices
Date: Thu, 10 Jul 2003 09:39:35 -0500
From: "Glass, Peter" <Peter.K.Glass AT WELLSFARGO DOT COM>
Subject: TSM and mod-27 devices
To: ADSM-L AT VM.MARIST DOT EDU
_________________________________Top_of_Message_____________________________
____

We're running a V5 TSM Server on an MVS platform, and considering the use of
mod-27s for its DASD needs.
Are there any known issues regarding the use of mod-27 DASD devices for TSM
db, log, or backup/archive pool volumes?
Thanks, in advance.

Peter Glass
MVS Storage Management

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