HP StorageWorks XP24000/XP20000 Performance Control User's Guide (T5214-96047, December 2008)

Figure 7 Traffic at ports
For detailed information about monitoring traffic, see
“Setting Priority for Ports on the Storage System” on page 36 and
“Analyzing Traffic Statistics” on page 35.
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, it is recommended that the upper-limit be approx-
imately 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 36.
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:
• Specify one threshold for each prioritized port.
In network A, if you specify a threshold of 200 IO/s for the port 1A and specify a threshold
of 100 IO/s to the 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 the port 1A is 200 IO/s or lower.
• The I/O rate for the port 1C is 100 IO/s or lower.
• Set only one threshold to the entire storage system
In network A, the desirable 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) reach 500 IO/s.
For details on how to set a threshold, see “Setting a Threshold ” on page 37.
XP24000/XP20000 Performance Control User's Guide 29