Disaster Recovery for Brokerage Firm’s Sizzling-Hot-Takeover


A leading brokerage firm located in the Midwestern U.S. needed to implement data replication to provide a redundant active/backup HPE NonStop Server system for a “sizzling-hot-takeover” in the event of a primary system failure.

Shadowbase Solution – Active/Almost Active Backup Disaster Recovery: collision-resolution-via-data-content

  • In this configuration, the active and backup nodes are identically configured with active bi-directional replication used to maintain synchronism between the two databases.
  • However, though the applications are active on both nodes, client interactions (broker requests) are only directed to the primary node.
  • In the event that the primary node fails or is taken offline, routers switch the clients to the other node within a sub-second time frame.
  • Since the application is already active (up and running and waiting for requests) on the backup node, takeover is virtually instantaneous and imposes very little impact on user processing.
  • It is impossible to tell which node is the primary node and which is the backup node. They are both identically configured, with all processes active at all times.
  • To test the system’s fail-over capability, management often forces a router switch to reverse the nodes.
  • It is extremely important in a fail-over architecture to actually test the disaster recovery plan to make sure that it works, ensure that the disaster recovery plan stays up-to-date, and that the operations staff is well-versed in the process.

Additional Shadowbase Benefit – Avoiding Planned Outages:

  • The brokerage firm also takes advantage of off-loading queries and reporting from the active node, which makes it extremely easy to avoid planned outages due to the need to upgrade a node.
  • When such an upgrade is needed, the router feed is switched to the other node, replication to the downed node is stopped, and the upgrade is performed.

Contact us for more information on this Shadowbase solution

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.