Letter of Justification


Burton Rosenberg
August 9, 1995

Introduction

This Letter of Justification concerns the acquisition of a Silicon Graphics server, supporting software, and maintenance contracts. (See attached quote.) The Department of Mathematics and Computer Science requires this server for the following three tasks.

  1. As the basis for Undergraduate and Graduate computing, including accounts for majors and coursework computing.
  2. To prolong the usefulness of existing computational infrastructure by sharing the workload and allowing maintenance down-time.
  3. To provide capability for migration from client/server to new architectures more suited to the needs of departmental faculty.

The choice of the Silicon Graphics Challenge S server was made with detailed consideration of these tasks, and in comparision to the IBM C20 server and the Motorola E100 Power Stack. We currently own DEC 5000's, a variety of Sun machines, a DEC Alpha, several VAX's, and several Pentium and PowerPC based machines, and our experience with these machines allowed us to reject them early on as insufficient for this application.

The Silicon Graphics machine was chosen because:

  1. It has far superior I/O performance than any competitor;
  2. It has slightly superior CPU performance but with a clear CPU upgrade path comprising processors which are currently employed in SGI's supercomputer class machines;
  3. It has excellent Unix based software including a full complement of Silicon Graphics' leading edge graphics library support and support of AppleTalk internetworking;
  4. It has networking options compatible with all contingencies of the University's LAN and WAN deployments;
  5. And, with its aggressive discounting for universities, it is approximately the same price as its competitors.

Justification Per Paragraph 5

[a.] Proposed system has been benchmarked for proposed usage. We benchmark the system by a comparison to current installed hardware. We now share the workload over a DECStation 5000/240 and a SPARCsystem 370. I estimate this machine to be 10 times more powerful than either.

A factor of five will come from new technology in the CPU. DECStation's run the R3000 family MIPS. DEC's next step was to cease the relationship with MIPS to create the Alpha AXP. MIPS is now whole owned by Silicon Graphics and they pursue the design family further. The Challenge R4400 at 200 MHz has performance equal to a 150 MHz Alpha chip on double precision Linpack. The Sun runs the Sparc 4 and is several generations behind either of these chips. We consider the R4400 at 200 MHz to be similar to the SuperSparc II running 75 MHz.

We expect an addition factor of two in going to 20 MHz Wide SCSI, compared to 10 MHz SCSI now employed. In addition, the Challenge provides 2 SCSI channels, which if used wisely will give up to a factor of two performance boost as well.

[b.] Multiple vendors have been considered. We have directly compared the Challenge S to the IBM C20 and the Motorola Power Stack E100. The backplane 267 MBS backplane of the Challenge S is twice that of the Motorola, furthermore it has 2 separate such extension backplanes and a separate high speed 400 MBS CPU to Memory channel that neither the IBM nor the Motorola have. The other machines are based on 100 MHz 604 with no clear upgrade path. The R4400 as evolved from the R2000, R3000, R4600, and we see ahead of us the R10000 with performance at 200 Spec Int and 300 Spec Fp.

Of the three, Silicon Graphics is the most experienced software provider and the software costs were reasonable.

[c.] An adequate software plan does exist. Concurrent with the acquisition is the purchase of all software and a three year software maintenance plan.

[d.] The software/hardware integration plan: The machine will occupy the same physical location as the current servers. As a Unix machine running NFS, it will interoperate fully with the other servers right out of the box. A special mission for this server is to interoperate with the growing community of MacOS users and we the purchase includes software to advance this goal.

[e.] The machine will function adaquately for the future. With a schedule of two upgrades at 2 and 4 years, it is our intent to maintain this machine at the state-of-the-art for 6 years.

[f.] The economic support plan: Concurrent with the acquisition is the purchase of a three year hardware and software maintenance plan. On site support includes our current system administrator and several faculty with considerable experience in maintaining Unix-based systems. The upgrades mentioned in item ``e'' are: the purchase of high speed Wide SCSI disks within 2 years; the purchase of a R10000 CPU upgrade within 4 years. Estimating price for these items and two additional years of maintenance, the total cost including purchase of this server will be \$7,000 a year.

[g.] The impact to the University: This purchase will aid the University by freeing up campus-wide resources to pursue improvements in the computing environment on the campus-wide level.