# Presentation: 035227

## Cluster Usability Panel

- What works for Cluster Computing?
- Mark Seager
- Fourth Workshop on Distributed Supercomputers
- March 10, 2000

## Professional Background

**PhD in Numerical Analysis from University of Texas at Austin, 1984**
**Worked in parallel numerical methods development, 1983-1991**
**Worked in parallel architecture simulation and tools development 1991-1993**
**Computer Center Project Manager, 1993-1997**
**ASCI Principle Investigator for TeraScale Platforms at LLNL, 1995-Present**

## What are cluster user roles/perspectives?

**Bottom Feeders**
**Computational scientist that need cheapest cycles possible!**
**Forced to use clusters to get enough capacity/capability (e.g., QCDSP)**
**Perspective is “clusters are an evil necessity, do enough to get the job done”**
**Working set is small group, limited budgets, science first.  Single application**
**Cluster Research & Development**
**Cluster research & developers**
**Applications/Algorithms research and development**
**Perspective is “clusters are cool tools, lets see what they can do!”**
**Working set is typically small groups focused on single projects, cluster first.  Small number of applications**

## What are cluster user roles/perspectives?

**Production (GA) Users - ****Capability**
**Code development for large multi-disciplinary  applications in the national interest...**
**10% of users use 90% of cycles.  Key users change over time.**
**Focus on code development, running production codes.  Range of jobs (boulders and sand)**
**Stability is a primary focus, scalability (minimal pain for maximal gain), appropriate tool for the job.  **
**Disparate groups, thousand applications.  Management chain.  **
**LONG RUNNING INTERDEPENDENT PRODUCTION JOBS WITH MULTIPLE STAGES.  **
**Full service computer/visualization center required...**
**Competent vendor partner required!!!!**

## Capacity at the capability level is required for milepost calculations.  ASCI code development requires multiple parallel streams of jobs

**bug identified**

**Week 1**

**Week 2**

**Week 3**

**Week 4**

**bug fix developed**

**bug fixed**
**In code**

**1,024 processor full scale run**

**128-256 processor reduced scale run**

**S **

**K **

**K **

**Time when old bug would have showed up**

**Sector**

**Capacity at the capability level is required for milepost calculations.  ASCI code development requires multiple parallel streams of jobs**

## Code 2 milepost plan requires extensive use of SST and some MuSST calculations in CY00!

- 1Q

- 2Q

- 3Q

- 4Q

- Full scale
- 1,024 proc.
- Primary burn run

- Rad Flow
- Milestone

- Secondary burn
- Milepost

- Code “tune-up”

- Preparation for CY00 milepost/stone

- Full scale
- 1,500 processor
- rad flow run

- S

- Reduced scale 128 proc.
- Primary burn run

- S,K

- Code “tune-up”

- K

- Reduced scale 375
- processor rad. flow run

- Reduced scale 375 proc.
- secondary burn run

- Full scale 1,024 proc.
- Physics module testing

- Partial and Full scale (1-1,500 proc.)
- Physics module development/testing

- Partial and Full scale
- (1-1500 proc.) Physics module
- development/testing

**Code 2 milepost plan ****requires extensive use of SST and some MuSST calculations in ****CY00****!**

- Code 2 requires several major physics modules to each operate on 1,500 processors

- Primary burn
- Milepost

- MuSST

- Full scale
- 1,500 processor
- secondary burn run

- Attempts to exceed minimum
- secondary burn milepost req

- CY00

## What are cluster user roles/perspectives?

**Production (Generally Available) Users - ****Capacity**
**Focus on science (not computational science).  Problem being solved dictates computational method and power required.  **
**Perspective is achieving company or program goals Application Physics**
**Stability is a primary focus, scalability (minimal pain for maximal gain), appropriate tool for the job.  **
**Disparate groups, thousand applications.  Management chain.  Few capability jobs.**
**LONG RUNNING INTERDEPENDENT PRODUCTION JOBS WITH MULTIPLE STAGES.  **
**Full service computer center required...**
**Reasonable vendor support required**

## What are cluster user roles/perspectives?

**Production (GA) Providers**
**System usage for others**
**System admin, configuration management, testing**
**Accounting, system management**
**Single system image**
**Stability**

## Success metrics for Production user groups

**STABILITY AND PREDICTABILITY FOR LARGE USER COMMUNITIES**
**Getting the science done!**
**Job turn around (response) time**
**System utilization**
**Ease of use**
**Richness of code development **
**Richness of production tools**

## What are the workarounds/tradeoffs?

**Development of system features while supporting Production workload**
**Rapid insertion of new HW/SW technology**
**Stability and predictability**
**Distribution of system resources (machine balance)**
**I/O, login, networking, accounting are all taxes on computation**
**How much compute vs. size of SMP vs. memory/node vs. I/O capacity and bw**
**Time to solution**
**Raw computing capability**
**End-user productivity**

- VS

- VS

## What are examples of cluster SW environments that excel at delivering?

**Meiko CS-2 (RMS)**
**Provided single system image**
**Single login, resource management**
**Symmetric programming model**
**Global file system**
**Great code development environment (PGI compilers, Etnus TotalView and standard Solaris code development tools)**
**Great portability between workstation (Solaris) and MPP**
**Local and global I/O model**
**Leveraged applications into ASCI program**
**IBM SP (PSSP)**
**Exact same system/programming model as Meiko (Solaris ******** AIX)**
**SMP environment is growing over time**

## SP Software Architecture

**Application**
**Enablers**

**System Management**
**Tools **

**Application**
**Development**
**Tools**

**Functions / Utilities**

**Applications**

**Hardware**

**AIX Operating System**

**Parallel System Support Programs**

**System Management Functions **

**Virtual Shared Disk       Recoverable VSD**

** ****RS/6000 Cluster Technology  CSS HACWS  PTPE**

**Hydrodynamics/Turbulence**
**Radiation Transport**
**Monte Carlo**

**LoadLeveler**
**GangLL**
**Tivoli TME 10 Family**
**Other  Tools**

**RDBMSs**

**OLTP Monitors**

**Parallel Env't**
**Subroutine Lib's**
**SMP Compilers**
**TotalView **

**NetTAPE**

**CLIO/S**

**GPFS**

**HACMP**

**Service Director**

**Visualization**
**Radiation Transport**
**Monte Carlo**