HP XP7 Storage - Manual (Page 51)

Figure 9 Upper limits for non-prioritized WWNs in Network B
After upper limits have been applied, the traffic is measured again to check the result of the upper
limits and see whether host performance has improved to a desirable level, in this case 400 IO/s
for wwn01. If not, you can adjust the upper limit to a smaller value until the I/O rate for wwn01
reaches the desirable level.
If you want to allow higher performance for non-prioritized WWNs when system activity is low,
you can apply a threshold. For many-to-many connections you can specify one threshold for the
entire storage system, regardless of the number of prioritized WWNs. For example, if there are
three prioritized WWNs in the network and the threshold is 100 IO/s, the upper limit on the
non-prioritized WWNs is disabled when the sum of the I/O rates for all three prioritized WWNs
falls below 100 IO/s.
The following table shows the relationship between the thresholds of prioritized WWNs and the
upper limits of non-prioritized WWNs.
Table 2 Relationship between the thresholds of prioritized WWNs and the upper limits of
non-prioritized WWNs
Upper limit of the non-prioritized
WWN = 0 Upper limit is set (non-zero) to the non-prioritized WWN Threshold settings
The threshold control of the
prioritized WWN is not executed. When thresholds are set to prioritized WWNs,
depending on the I/O rate or the transfer rate, the
following controls are executed. Threshold is set to the
prioritized WWN
•
If the total value of I/O rate or transfer rate exceeds
the threshold in all prioritized WWNs, upper limits
of all non-prioritized WWNs are in effect.
•
If the total value of I/O rate or transfer rate goes
below the threshold in all prioritized WWNs, upper
limits of all non-prioritized WWNs are not in effect.
The specified upper limit is always in effect. Threshold is not set to
the prioritized WWN
Cautions and restrictions for Performance Control
•
Real-time monitoring mode
Performance Control cannot be started when Performance Monitor is in real-time mode. Before
starting Performance Control, ensure that Time Range in the Monitor Performance window is
not set to Use Real Time.
•
Remote copy ports
When the remote copy functions (Continuous Access Synchronous, Continuous Access
Synchronous Z, Continuous Access Journal, and Continuous Access Journal Z) are used in
your environment, Performance Control monitors write I/O requests issued from the initiator
ports of your storage system.
If you set the priority attribute to an RCU target port, all I/Os received on the port are controlled
as the threshold control, and its performance data is added to the total number of I/Os (or
the transfer rate) of all prioritized ports. I/Os on the port will not be limited.
Cautions and restrictions for Performance Control 51