#### Roundtable Discussion

Current Primary Computing System:

Tammy Welcome pointed out that only six of the 43 respondents use
tightly coupled systems.

Impact of Increased Computing Resources:

Craig Tull: It's hard to know what science won't happen without
increased resources. It's more likely that current research will be
diminished without MRC. What science could we do better with MRC?

John Staples: Also, what science could we do faster, cheaper with
increased MRC resources?

Ali Belkacem: More people have unsatisfied demand for MRC -- but how do
we quantify this?

Source of Software:

Bill Fawley: Only a small group of people know how to effectively
utilize a bigger system.

Ali Belkacem: Could the Lab provide funding to help develop scientific
codes.

Craig Tull: Software has a limited lifespan, especially in cluster
computing.

How Parallelizable Is Your Code?:

Ali Belkacem: There are barriers to massively parallel processing (MPP).

Tammy Welcome: Is that barrier really there, or is there really not
enough demand for MPP?

Tom Daley: Help in parallelizing code would be useful, especially
centralized support help to answer questions.

Bill Fawley: There are 200 researchers in AFRD who use embarrassingly
parallel types of codes, but they can't tunnel through that quantum
barrier to parallelize their code.

Martin Head-Gordon: My group has a range of software projects that are
at different stages of development and heterogeneous. The group is
building up individual clusters and have questions about system support
and management, security issues and networking. We would benefit from
generic issue support.

Yuen-Dat Chan: MRC has a wider scope than MPP. We would like something
better than PDSF (faster turnaround). We would like to be able to
reserve resources for a single project.

Mario Cromaz: We don't use MRC now, but we are designing a detector and
will need HPC then, but not necessarily parallel processing. We will do
event reconstruction in real-time, an MRC resource will be attached to
the detector for data acquisition, and there will be so much data we
will need to process it immediately -- unable to store it all.

Greg Kurtzer: Real-time processing can be short-turnaround with very
fast imaging.

Craig Tull: PDSF, with LSF\< won't meet the needs of large, real-time
projects.

Michael O'Keefe: We need an MRC for an electron microscope, but are
unsure of the needed capacity.

Support:

Tom Daley: Help for people buying clusters would be useful.

Martin Head-Gordon: Responsibility for system management falls on
students and post-docs, and doesn't fall evenly. Support that is not
prohibitively expensive would be useful.

Sandy Merola: The more we buy clusters different from one another, the
harder it will be to realize economies of scales. ITSD is in early
stages of growing support for clusters.

Computer Room Space:

Martin Head-Gordon (seconded by Ken Reyzan): Providing space for
clusters is essential.

Shared Computational Resource:

Tammy Welcome: The problems with "alvarez" are due to an early delivery
of Myricom interconnect.

Ali Belkacem: With a little leveraging with NERSC, we could get a whole
lot of alvarez for the Lab.

Sandy Merola: To determine the path forward, we should pick either the
number of nodes desired or the amount of money available and then run
out a comparison of various resources.

Tammy Welcome: Are you interested in capacity or capability? We need to
know that.

Martin Head-Gordon: I would like to argue for a strategy and to follow
the Law of No Free Lunch. Why should we do anything other than shoe
stringing?

The University of Utah and Indiana University both provide central
computing facilities and should be investigated. However, it always
costs more to provide better service.

ITSD could help broker and facilitate upgrades, purchase of new systems
and finding partners for shared facilities.

The Path Forward:

The creation of a cluster news group was discussed, but most felt that
news groups weren't as effective as they used to be.

Sandy Merola: How do we determine if a shard resource is worth pursuing?

Craig Tull: We could invite potential users to try out existing systems,
such as PDSF, alvarez and the new CIS cluster. Also determine if the
general need is serial or parallel processing.

Bill Fawley: We don't know the costs of adding on to PDSF or NERSC's SP.
Until we know the costs, we can't really proceed.

Elizabeth Finlayson: There seems to be a lot of people interested in
sharing. ITSD could be helpful in setting up partners for "cluster
mates."

Greg Kurtzer: Should we set up a Lab-wide Cluster Users Group?

John Staples: We're not ready to consider new hardware until we know if
our software is parallelizeable. How do we take care of people who are
at this stage?

Final Roundtable Comments:

## Sandy Merola: The tone of the workshop indicates there is a better way to do things, but we're unsure what the path is.

Eric Hjort: I'm a big PDSF user and small users benefit from our
downtime -- they can get a foot in the door, but it's inconsistent. As a
path forward I recommend using PDSF as a model.

Greg Kurtzer: Smaller clusters can be optimized for the applications
running on it. Not one size of a cluster will fit everyone -- there are
different needs and perspectives. There is a need for a small group to
consult with about codes to determine what you need and what's the best
approach.

Rob Ryne: Scientist-to-scientist support would be extremely useful. I'm
pessimistic about shared resources -- alvarez is unstable and I can't
get excited about augmenting PDSF to run serial jobs. Piggybacking on
NERSC is a political challenge. It would be useful to set up a web site
to gather information about clusters at the Lab. That way we could talk
to other cluster users and find out what did and didn't work. If people
have to spend \$50K a year to manage 30 nodes, they won't do it.

Bill Fawley: There is not one solution for all needs. More time on the
nodes of NERSC's SP is the easiest way to get HPC. As to Linux clusters,
it's unfortunate ITSD hasn't set up its own cluster that it could
subsidize as a "loss leader."

Esmond Ng: I'm surprised the discussion focused on clusters. I'm not
sure that scientific applications at the Lab can use cluster computing.

John Staples: There is a lot of distributed knowledge about clusters --
we should bring it together to help those who are using clusters. There
may be a lot of people like me on the cusp. If we make it easy to enter,
we may get more people into the water. An easy way to test software to
see if it works on a cluster would be a good entry path. If we are going
to continue, we need to get people in a room talking about it.

Tammy Welcome: One option might be to harness systems on desktops.

Eric Esary: Most of our needs are currently met by NERSC. We might use a
cluster if it was available, but I can't see the advantage.

Michel Van Hove: I would like to see the financial details. Pre-purchase
consulting and "matchmaking" between partners would be useful.

Alessandra Ciocio: We need to keep the contacts going and schedule
meetings for further discussion.

Paul Adams: The ability to use a centralized computer room is important.
We bought SMPs to simplify system administration. I'm pessimistic about
sharing resources.

Tom Daley: Pre-purchase consulting and a central computer room would be
useful. One MRC won't fit all. Small clusters should be optimized for
specific applications -- sharing them is counterintuitive. We might need
two or three MRC resources. Getting help for people buying small systems
is important.

Martin Head-Gordon: We are already down the cluster road. The issue is
what can ITSD provide at a modest cost to fit in existing budgets --
housing clusters, what-to-buy expertise. As proposed, sys admin is too
expensive. We don't like Linux, not true 64-bit processing.

Ken Downing: I think we will be following several paths. For many,
joining PDSF is a good option. Offering a "loss leader" ITSD cluster is
a good idea.

Mike O'Keefe: Hardware has been well covered here, but we can't lose
track of software problems. Software training in parallelization is
useful.

Shaheen Tonse: People who haven't parallelized their code yet could be
encouraged to go the SMP route. Early economies of scale could be on the
order of 50 percent.

Ali Belkacem: We're not ready for sharing resources. System management
is too expensive -- we need to be able to provide it at an affordable
cost. We have to get people who are using the resources together to
increase the sharing of resources. I don't see PDSF as a good option for
political reasons. We have to make the scientific case for an MRC
resource. If we can't make that case, we won't get there. We need help
from the rest of the Lab.

Elizabeth Finlayson: It's important to be able to do our research faster
and better. If we can't do it faster, we won't be doing it at all. It
would be useful to provide centralized training fro cluster system
administration and have a user group of cluster managers.

Sandy Merola: Everything in IT is moving toward people doing it
themselves.

Craig Tull: We need to get concrete answers to the above questions
before we meet again.