The Need for High Availability in Data Center Switches
High availability is essential today, especially in industries with strict compliance and regulatory requirements such as financial and legal services and government. In an enterprise SAN, director-class switches are expected to be robust and reliable; failure to provide high availability can mean a significant loss of revenue, productivity, and reputation.
Objective of the Test
A fabric module is responsible for switching traffic across various ports on the directors. A SAN director usually has two fabric modules for high-availability, so that even if one fails, the traffic is not completely interrupted. In this document "fabric module" refers to the Fabric Module 2 for MDS 9513 Multilayer Director, to the Supervisor 2 for MDS 9506/9509 and to the Core Routing module for the competitor's 8-Gbps Director.
The test was performed to evaluate the availability of SAN directors when subject to a fabric module failure. The test simulated fabric module failure while traffic was applied through the director switch; the test then computed the frame loss and the forwarding outage time per port.
Test Equipment Configuration
The competitor's fabric module cannot be removed without powering it down first, so no direct removal test was performed for the competitor's director.
Real-World Application Environment
This test was repeated to observe the implications for real-world applications of the lack of high availability in the competitor's director. Instead of using the Agilent SAN Tester to generate the test data and measure the frame loss, an Oracle simulation was run, using HammerOra to generate the test data and measure the results while the Core Routing Module was turned off and on. This test allowed evaluation of the effects of frame loss at the application layer. The test configuration consisted of one server running the Oracle test script against an Oracle database on an array.