Modernizing Mainframes at Goldman Sachs

Table of Contents

1. Business Case
2. Legacy Design
3. Reinvented Design
4. Replatforming Approach
5. SDLC Development for COBOL
6. Lessons Learned

1. Business Case

• The GS Asset Management division oversees more than $2 trillion in assets, making it a top 10 global asset manager.
• The portfolio accounting system, InvestOne, is a critical mainframe workload that has been in use for over 30 years.
• InvestOne consists of a vendor-provided software (InvestOne by FIS) and a Goldman-built COBOL orchestration layer.
• Key business challenges include:
  • Vendor pushing to migrate off mainframe
  • High cost of running on mainframe
  • Complexity and limited integration capabilities
  • Difficulty sourcing skilled COBOL engineers
  • Inability to scale the system horizontally to support business growth

2. Legacy Design

• The InvestOne system is a monolithic architecture running on the mainframe.
• It integrates with various upstream (data producers) and downstream (data consumers) systems using batch and real-time messaging (MQ, SFX).
• The core components include:
  • Operating system (z/OS)
  • File storage (DB2, VSAM, Flat files)
  • Middleware services (CICS, TSO)
  • Vendor-provided InvestOne core and Goldman's COBOL orchestration layer
  • Scheduler for event-driven processing
  • Mainframe-embedded SDLC

3. Reinvented Design

• The key objective is to replatform the existing InvestOne system to AWS without modifying the application logic.
• The core components in the reinvented design are:
  • Shared VPC with GS routable and cloud routable subnets
  • Mainframe emulator (NTT Data) running the COBOL runtime
  • Scheduler service (replacing mainframe scheduler)
  • RDS database (replacing mainframe databases)
  • S3, SNS, CloudWatch, EventBridge, and other AWS services

4. Replatforming Approach

• Decided to take a replatforming approach (lift-and-shift) to expedite the migration and enable future modernization.
• Designed a resilient architecture with active-active deployment across two AWS regions.
• Leveraged AWS services like DRS (Disaster Recovery Service) and SSM (Systems Manager) to manage the EBS volumes and orchestrate the workflows.

5. SDLC Development for COBOL

• Developed a custom SDLC using a combination of internal and open-source tools:
  • Nix for packaging, Coder for developer workspaces
  • VS Code with COBOL plugin for IDE
  • GitLab for source control and CI/CD

6. Lessons Learned

• Getting the system running on the emulator is the first step, but there is a significant amount of work required to recreate the entire environment.
• Maintained consistent interfaces with the existing consumers and producers of data to reduce the blast radius.
• Adopted a pragmatic approach of replatforming first, then exploring further modernization opportunities.
• Leveraged AWS expertise and resources to supplement the Goldman team's knowledge and capabilities.