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The performance optimization function provides the capability of "Bottleneck Detection Support", "Replacement Plan",
"Replacement Effect Prediction", and "Performance tuning". This section describes outlines of the functions.
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Concentration of I/O in a specific physical disk causes I/O competition thereby deteriorating response. The degree of
concentration of I/O in a physical disk can be indicated as the physical disk's operating time per unit time. This value
is expressed as the physical disk's Busy Ratio.
The NEC Storage PerformanceOptimizer monitors the load state of physical disks at specified intervals and displays
the obtained Busy Ratio for each physical disk on the dedicated client screen. Analysis of the Busy Ratio displayed
on the dedicated client screen allows you to detect a physical disk (bottleneck location) in which I/O concentrates.
The NEC Storage PerformanceOptimizer features the following display of the Busy Ratio, which enables the analysis
suitable for the business system and visual detection of the bottleneck.
The analysis period (Busy Ratio calculation period) can be specified in terms of the exponent condition for the date,
days of the week, and time zone.
Display a Busy Ratio in tri-level with color-coding.
Display over-time changes of Busy Ratio in three different colors.
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Upon detecting a physical disk with concentrated I/Os (bottleneck part), logical disks are moved (replaced) to tune
performances. This function displays information about the movement destination logical disks, which re best suited
for the source logical disk. This function automatically finds the movement destination logical disks that are highly
effective for I/O distribution after moving disks, and displays the disks in the order of effectiveness. An administrator
is allowed to tune the performances on the basis of the information and remove the bottleneck.
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An effect of load distribution after logical disk movement can be estimated before logical disk movement. This
function displays the changes of Busy Ratios in source and destination logical disks or RANK, in graph format. An
administrator is allowed to verify that I/O will not concentrate after moving disks, and tune the performances on the
basis of the estimated effects.
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The NEC Storage PerformanceOptimizer moves logical disks located in a high load physical disk in which I/O
concentrates to a low load RANK so as to distribute the concentration of I/O thereby canceling the I/O competition and
removing the bottleneck. This is called performance tuning. The performance tuning can be executed instantly, or at
a registered time.
Figure 4-2 shows the concept of performance tuning implement by the performance optimization function. The work
disks shown in the figure are logical disks dedicated to the use for the performance tuning (The Work Disk for
Chapter 4 Overview of Performance Optimization Function
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