Homogeneous Active/Active Systems for Regional Bank Service Bureau

Problem:

A large U.S. bank implemented a service bureau application to support smaller regional banks to offer/process securities and financial information to their customers. The service bureau required an active/active architecture that would provide load-balancing and continuous availability. Due to various outages that sometimes occur during hurricane season in the Florida HPE NonStop node, the bank also required a system that would allow for fast failover of their users to the Midwest NonStop node.

HPE Shadowbase Solution: Homogeneous Active/Active SystemsCollision avoidance via partitioned users is illustrated in Figure 1. Both databases are configured in an active/active, bi-directional configuration. The users are load-balanced across nodes, with users A-M assigned to the Midwest node, and users N-Z assigned to the Florida node. Since the application is partitioned and users are separated between nodes, there is no opportunity for data collisions to occur.

Homogeneous Active/Active Systems for Regional Bank Service Bureau

Figure 1 — Collision Avoidance via Partitioned Users

  • Data changes on each HPE NonStop node are applied to the other NonStop node’s database via asynchronous replication.
  • The primary databases for the bank’s customers are assigned to one of the two nodes (Midwest or Florida) in order to load-balance activity across both nodes, which is periodically evaluated and adjusted for load-balancing purposes depending on the volume of the changing transactions.
  • To avoid data collisions using this approach, it is important that the database supports partitioning (via a customer identifier embedded in the record key fields) and that an update for a specific customer is always executed on the same node.
  • If a node fails, all of its users are reassigned to the second node.

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The above was adapted from the book: Breaking the Availability Barrier, Volume III: Active/Active Systems in Practice by Paul J. Holenstein, Dr. Bruce Holenstein, and Dr. Bill Highleyman.