HP XP7 Storage - Manual (Page 48)

If you want to allow improved performance for non-prioritized ports when system activity is low,
you can apply a threshold. For one-to-one connections threshold values can be set in either of the
following two ways:
•
Set a threshold to each prioritized port.
In Network A, if you set a threshold of 200 IO/s to port 1A and a threshold of 100 IO/s to
port 1C, the upper limit on the non-prioritized port (2A) is disabled when both of the following
conditions occur:
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 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) falls below 500 IO/s.
The following table shows the relationship between the thresholds of prioritized ports and the upper
limits of non-prioritized ports.
Table 1 Relationship between the thresholds of prioritized ports and the upper limits of non-prioritized
ports
Upper limit of the non-prioritized
port = 0 Upper limit is set (non-zero) on the non-prioritized port Threshold settings
The threshold control of the
prioritized port is not executed. When thresholds are set on multiple prioritized ports,
depending on the transfer rate, the following controls are
executed: Threshold is set to the
prioritized port
•
When the I/O rate or transfer rate goes above the
threshold in any prioritized port, the upper limits of all
non-prioritized ports are in effect.
• When the I/O rate or transfer rate goes below the
threshold in all prioritized ports, the upper limits of all
non-prioritized ports are not in effect.
The specified upper limit is always in effect. Threshold is not set to
the prioritized port
Use case for many-to-many connections
The following figure shows an example of a network, called Network B, in which a production
server and a development server are connected to the storage system in a many-to-many
configuration. HBA wwn01 on the production server is connected to ports 1A, 2A, 1C, and 2C,
and HBAs wwn02 and wwn03 on the development server are also connected to the same four
ports.
48 Performance Control operations