A6826A - PCI-X Dual Channel 2Gb/s Fibre Channel Adapter Performance Paper for Integrity Servers

3
Test results
HP obtained the performance data presented in this paper using the diskbench (db) benchmarking utility. Various
block size tests were executed for read and write on single and dual ports. The IOPs metric was obtained with 1
KB block size transfers. The throughput metric was obtained with 128 KB block size transfers. The throughput
metric is useful in modeling large sequential transfers, for example, remote backup. The IOPs metric is useful in
modeling small transactional traffic.
IOPs
Chart 1a: IOPS Chart 1b: % CPU Utilization
Chart 1a shows the number of I/O operations per second for read and write operations on a single port and on
both ports of an A6826A adapter measured on a 4 way rx4640 server. The X-axis represents the number of Fibre
Channel ports and the Y-axis represents the number of I/O operations per second.
Chart 1a shows linear scaling of IOPs for one and two ports. The number of read I/O operations per second for a
single port and for dual ports is 35180 and 70032 respectively. The number of write operations per second for a
single port and for dual ports is 20619 and 41221 respectively. The IOPs metric is limited by the processor used
on the A6826A adapter.
Chart 1b shows the %CPU utilization for I/O operation tests. The X-axis represents the number of Fibre Channel
ports. The Y-axis represents the % CPU utilization. To accurately record CPU utilization, only one CPU was
configured in these tests. Chart 1b demonstrates excellent CPU utilization numbers for small size I/Os on both
ports of an A6826A adapter.
Service demand
Service Demand is a measure of the CPU time needed to handle 1 KB of I/O. The Service Demand number for an
adapter is a measure of how much load the adapter places on the CPU(s) for each KB/s of throughput. The
A6826A adapter offers low CPU service demand for small I/Os. To illustrate the service demand for the A6826A
adapter, small size operations tests were conducted using db. Sequential Read and Write operations of 4KB and
8KB I/O sizes were performed on an rx4640 server with one CPU configured.
The following table shows single and dual port throughput and CPU utilization for raw Sequential Read and
Sequential Write operations with 4KB and 8KB I/O sizes:
Number Sequential Read Sequential Write
0
20000
40000
60000
80000
IOPs
Read
35180 70032
W
rite
20619 41221
1 Port
2 Ports
0
20
40
60
80
% CPU Utilization
Read
39 73
W
rite
27 46
1 Port
2 Ports