Determining if Performance Accelerator will increase system performance

Server and Cluster Administration Guide for Hitachi NAS Platform

Part Number

To evaluate the current throughput component, measure the current system throughput. If the current system throughput is close to the “standard” throughput limits, then it is likely that the PCIe connection to the Tachyon Fibre Channel controller is not optimized for performance. Performance Accelerator might bring a performance improvement. The standard read speed, on newer systems equipped with QE4+ Tachyon controllers, is 880 MB/sec; the standard write speed is 800 MB/sec. On older systems, equipped with QX4 Tachyon controllers, the standard read speed is 880 MB/sec; the standard write speed is 640 MB/sec.

For the IOPS component, collect a PIR while the system is under maximum load. Examine the SI utilization by looking at the "si_busy_clocks_last_second_percentage statistic" in the logged-statistics.csv file. If this file shows that the SI FPGA is very busy (at 90 to 100 percent active, with the standard being 72,000 ops/sec), then it is likely that the SI cache controller is not optimized, and Performance Accelerator might significantly improve performance.