WAN configuration considerations for IOPs
When configuring a communications controller, you should consider both
subsystem storage and aggregate line speed. Subsystem storage is the amount
of storage available on the communications controller. Aggregate line speed
is the sum of individual lines speeds that are attached to the communications
controller.
The following information can help you understand network configuration
considerations for input/output processors (IOPs).
- For interactive environments, you should not exceed 60% use on the communications
IOP. Exceeding this threshold in a large transfer environment or with a small
number of concurrent users might still offer acceptable performance. Use the iSeries™ system performance tools to get the utilization.
- You can attach multiple IOPs to an iSeries system. The maximum number of IOPs
that can be attached is determined by the iSeries server model. It is important to distribute
the work load across several IOPs if the performance capabilities of a single
IOP are exceeded.
- Even though an IOP can support certain configurations, a given iSeries server model
might not have enough system resource (for example, CPU processing capacity)
to support the work load over the lines.
- The use of larger frames generally improves large transfer performance
in terms of capacity for the communications IOP and in terms of system response
time. The amount of time that the IOP spends processing a larger frame is
only slightly more than the amount needed to process a smaller frame. If you
use larger frames to transfer a single system message or block of data, the
total number of frames required to complete the transfer are decreased.
- The values for IOP use in synchronous data link control (SDLC) environments
do not necessarily increase consistently with the number of workstations or
with the workload. An IOP can spend more time polling when the application
is not using the line. It is possible to see a relatively high IOP use at
low throughput levels.
book.