To set a common ground for our comparison, the vendors were asked to select one SAN, consisting of a single array with two disk enclosures plus two FC switches and the management software, and to provide the list price for that configuration.
I set two stages for the testing. First, evaluate each solution independently; second, consolidate the three SAN islands under the same fabric, with the objective of making all of my application servers able to provision storage from any array, and possibly to centralize storage management across different solutions.
I rated the solutions according to these criteria: interoperability, management, performance, reliability, and value.
Establishing general criteria to assess performance for complex systems such as the ones that I reviewed is difficult. In addition, customers look at performance from different angles. For a critical application, the responsiveness to servers' I/O operations is critical, and is also easier to access using load simulators such as Iometer. However, this approach doesn’t take into consideration the overall performance of the storage system, which is very difficult to measure.
Nevertheless, I used Iometer scripts to simulate read/write traffic between servers and storage arrays, running multiple scripts concurrently to emulate increasing load conditions, and verifying that the test results were within the performance range published by each vendor.
For management testing, I observed the vendors’ engineers executing a series of basic management tasks including configuring HBAs and FC switches; creating , resizing and deleting LUNs; defining and modifying zones; and discovering and remedying faults caused by a simulated disk or FC connection failure creating volume.
I also ran these tests independently and, to test reliability features, in combination with load simulation on target hardware, noting the impact of a failure on active applications.