IBM eServer POWER5 Processors Virtual SCSI Throughput Analysis

With the arrival of IBM POWER5™ processor-based systems, advanced virtualization capabilities, including Micro-Partitioning™ and Virtual I/O, have significantly extended IBM's leading-edge virtualization technologies.

This throughput analysis highlights Virtual SCSI performance on the IBM eServer™ p5 570 system with the AIX 5L™ V5.3 operating system. This study is a follow-on to the previous "IBM eServer POWER5 Virtual SCSI Processors Performance Study".

Throughput, as a measure of the amount of work performed over a period of time, is an important performance expectation. This paper describes the effects of varying throughput, including workload used, systems configuration, performance tools, benchmark test script, performance results and conclusions.

This analysis examines the performance of a Virtual SCSI (VSCSI) implementation using the Iozone workload. Local I/O is compared with Virtual I/O using FAStT (DS4500) and SCSI configurations at various throughput levels. Additionally, the effects of simultaneous multi-threading vs. single threading (ST) are considered.

VSCSI implementation is highlighted as a solution for clients looking to consolidate I/O resources with a small amount of processor overhead. The new Virtual SCSI capability on POWER5 systems creates new opportunities for consolidation, while demonstrating strong performance and manageability.

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