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3. Set an upper limit to 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 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 Priority for Ports on
the Storage System.
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 has reached to a
desirable level. If production server performance is not improved to a
desirable level, 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 rate for 1A and 1C is still below 400
IO/s, the administrator needs to change the upper limit until the I/O rate
reaches 400 IO/s.
5. If necessary, apply a threshold. If you want to use threshold control, set
threshold values in the Port tab in the Server Priority Manager window.
You can set threshold values in either of the following ways:
– Set one threshold to each prioritized port
In network A, if you set a threshold of 200 IO/s to the port 1A and set 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, if you set a threshold of 500 IO/s to 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 Upper-Limit Control.
Hitachi Universal Storage Platform V/VM Hitachi Performance Manager User's Guide
Server Priority Manager Operation
6-5
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