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6. Check the result of applying upper limit values. After applying upper limit
values, you must measure traffic at ports. View traffic statistics for the
prioritized WWN to check whether the host performance is improved to a
desirable level.
In network B, the desirable I/O rate for the prioritized WWN 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 B, if the upper
limit is set to 720 IO/s but the I/O rate for wwn01 is still below 400 IO/s,
the administrator needs to change the upper limit until the I/O rate reaches
400 IO/s.
If an upper limit of the non-prioritized WWN is set to zero or nearly zero,
I/O performance might be lowered. If I/O performance is lowered, the host
cannot be connected to the storage system in some cases.
7. If necessary, apply a threshold. If you want to use threshold control, set a
threshold in the WWN tab in the Server Priority Manager window.
In the WWN tab, you can specify only 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 prioritized WWNs goes below 100 IO/s.
For details on how to set a threshold, see Setting a Threshold.
Caution: If you enter zero (0) in a cell to disable the upper limit, the cell
displays a hyphen (
ineffective. If the thresholds of all the prioritized ports are ineffective,
threshold control will not be performed but upper limit control will be
performed. If you set thresholds for multiple prioritized ports and the I/O
rate or transfer rate becomes below the threshold at one of the prioritized
ports, threshold control takes effect and the upper limits of the non-
prioritized ports are disabled. The following table shows the relationship
between the thresholds and the upper limits.
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Hitachi Universal Storage Platform V/VM Hitachi Performance Manager User's Guide
) and the threshold for the prioritized port becomes
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Server Priority Manager Operation
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