HP StorageWorks XP24000/XP20000 Performance Control User Guide (T5214-96087, September 2010)

I/O rate for prioritized ports (1A and 1C) at 400 IO/s. To maintain the I/O rate at 400 IO/s,
you must set an upper-limit to the I/O rate for the port 2A.
Figure 7 Traffic at ports
.
For detailed information about monitoring traffic, see “Setting Priority for Ports on the Storage
System” on page 34 and “Analyzing Traffic Statistics in the Port Tab” on page 33.
3. Set an upper-limit for the I/O rate for traffic at the non-prioritized port. To prevent decline in I/O
rates at prioritized ports, you set upper-limit values to the I/O rate for non-prioritized ports.
When you set an upper-limit for the first time, HP recommends that the upper-limit be approximately
90 percent of the peak traffic. In network A, the peak I/O rate for the non-prioritized port (2A)
is 200 IO/s. So, the recommended upper-limit for 2A is 180 IO/s.
For details on how to set an upper-limit, see “Setting Upper-Limit Values to Traffic at Non-prioritized
Ports” on page 34.
4. Check the result of applying upper-limit values. After applying upper-limit values, you must
measure traffic at ports. You must view traffic statistics for prioritized ports 1A and 1C to check
whether the host performance is improved to a desirable level.
In network A, the desirable I/O rate for ports 1A and 1C is 400 IO/s. If the I/O rate reaches
400 IO/s, production server performance is at a desirable level. If production server performance
is not improved enough, you can change the upper-limit to a smaller value and then apply the
new upper-limit to the storage system. In network A, if the upper-limit is set to 180 IO/s but the
I/O rates for 1A and 1C are still below 400 IO/s, the administrator needs to change the upper
limits until the I/O rates reach 400 IO/s.
5. If necessary, apply a threshold. To use the threshold control, set threshold values in the Port tab
in the Performance Control window. You can set threshold values in either of the following ways:
• Set one threshold for each prioritized port.
In network A, if you set a threshold of 200 IO/s for port 1A and set a threshold of 100 IO/s
for port 1C, the upper limit on the non-prioritized port (2A) is disabled when either of the
following conditions is satisfied:
• The I/O rate for port 1A is 200 IO/s or lower
• The I/O rate for port 1C is 100 IO/s or lower
• Set only one threshold for the entire storage system
In network A, if you set a threshold of 500 IO/s for the storage system, the upper limit on the
non-prioritized port (2A) is disabled when the sum of the I/O rates for all prioritized ports
(1A and 1C) goes below 500 IO/s.
For details on how to set a threshold, see “Setting a Threshold in the Port Tab” on page 35.
XP24000/XP20000 Performance Control User Guide 27