Roles for mainframe unix and UTS vs. AIX/370 questions

[John Sloan,8292,X1243,ML44E]

>From article <21015 at adm.BRL.MIL>, by DMOYNIHA%WAYNEST1.BITNET at cornellc.cit.corn (Dennis P. Moynihan):
> We're open to any other general comments you have on mainframe unix
> systems and UTS and AIX/370 in particular.  Thanks in advance!

I don't have any experience specifically with either UTS or AIX, but I
do have a few general comments (although from your questions I bet
you've already considered them). My perspective is that I spent years
as a systems programmer on IBM mainframes (360/65 and 370/3031) under a
variety of OSs (OS/MFT, MVT, SVS, MVS); for the past five or six years
I've been dealing almost exclusively with UNIX (both BSD and System
V).

I personally know of two AIX/370 shops, who chose AIX just because they
had IBM hardware and hence had IBM support.  You may end up using UTS
for the same reason.

One thing IBM/compatible mainframes are really good at is providing I/O
bandwidth, which makes them REALLY attractive as file servers. You may
want to consider though, that much of that bandwidth exists in the
communication paths between CPUs, channels, and controllers. Once you
leave this optimized I/O path, you may find that the channel and/or
network speed is not all that fast in comparison.  If you use the
mainframe as a fileserver over traditional access paths (i.e.
Ethernet) then it may turn out you've got this I/O path the width of
the Mississippi, all funneling through 2 inch diameter pipe.

In those hazy times when I thought about using a mainframe as a file
server, I've wondered if there was hardware to channel attach a
FDDI-based fiber network; if not, then a way to channel attach multiple
Ethernet interfaces, making each interface look to the outside world as
if it were attached to a separate file server (different Internet host
ids, etc.). I'd probably like to spread those Ethernet interfaces
across several channels, too. Depending on the statistical distribution
of channel usage for disks, tapes, Ethernet, etc. I might want to try
to optimize the combinations (if possible).

Finally, do you really need to run UNIX at all? Some possibilities:

o	Run AIX/UTS as the native operating system.

o	Run AIX/UTS under VM as a guest operating system.

o	Run AIX/UTS under PR/SM.

o	Run TCP/IP+NFS on top of MVS.

This latter alternative doesn't give you a big UNIX timesharing engine,
but it retains MVS functionality, without the overhead of VM or PR/SM,
and could still let you use the big iron as a file server (no claims
are made, though, about mapping UNIX file system semantics on top of an
MVS VSAM-based file system).

There are also network bandwidth/management issues regarding
centralizing a heavily-used file server resource; some of those same
issues crop up when you just put all your Sun (or whatever) file
servers off the same network cable (e.g. together in a computer
room).

As you come to conclusions, you would be doing the net a service
by posting a summary. I for one would be really interested in
hearing what you've decided, how you came to your decision, and
how it all works out in the end. I hope that eventually EDUCOM
publishes another volume similar to their ancient _Campus Computing
Strategies_ and their more recent, excellent, _Campus Networking
Strategies_, which covers some of these very issues with case
studies. Maybe a _Campus Integration Strategies_.

John Sloan            NCAR/SCD             NSFnet: jsloan at ncar.ucar.edu
P.O. Box 27588        P.O. Box 3000        NCAR Mesa Lab, Room 42A
Lakewood CO 80227     Boulder CO 80307     +1 303 497 1243
Logical Disclaimer: belong(opinions,jsloan). belong(opinions,_):-!,fail.