SOS Disk I/O Summary
The Disk I/O Summary Screen
The Disk I/O Summary screen provides a summary of performance data for all disks on the
system. This screen is available in graphical and tabular formats.
To access the Disk I/O Summary screen from any SOS display screen:
Type s from the SOS Enter command: prompt to view the Screen Selection Menu screen.
From the Screen Selection Menu screen, enter d (Disk I/O Summary). The Disk I/O Summary screen will display.
Type t to toggle between the graphical and tabular displays.
Disk I/O Summary Screen Display Items
Graphical Format
Figure 12.1 shows an example of the Disk I/O Summary screen in graphical format.
Figure 12.1 SOS Disk I/O Summary screen (graphical format)
DISK I/O SUMMARY (graphical format)
The DISK I/O SUMMARY data items are described in the following table.
Table 12.1 SOS DISK I/O SUMMARY data items
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Data Item
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Description
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Device
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The Device column in the left portion of the graphical DISK I/O SUMMARY lists each of the disk device identification numbers.
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Percent Utilization
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The Percent Utilization graph shows the percentage of time during the interval that the device was in use.
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I/Os per second
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The I/Os per second value in the graphical DISK I/O SUMMARY represents the number of physical disk I/Os on the disk per second. Similarly to the IO/s bar graph in the Global Summary screen, specific code letters in the bar graph tell you how many of each type of physical I/Os were accumulated in the current interval. The code letters are:
R represents the number of physical reads per second.
W represents the number of physical writes per second.
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TOTALS
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The TOTALS line shows the total utilization and disk I/Os per second for all disks.
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The tabular Disk I/O Summary screen is discussed on
113.
Tabular Format
Figure 12.2 shows an example of the Disk I/O Summary screen in tabular format.
Figure 12.2 SOS Disk I/O Summary screen (tabular format)
DISK I/O SUMMARY (tabular format)
The data items in the DISK I/O SUMMARY portion of the Disk I/O Summary screen are described
in the following table.
Table 12.2 SOS DISK I/O SUMMARY data items
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Data Item
|
Description
|
|
Dev
|
The device identification number for each disk on the system.
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I/O%
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The percentage of all disk I/Os on the system performed by each disk during the interval.
|
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Qlen
|
The average number of disk requests waiting to be serviced by each disk.
|
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Util%
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The percentage of time each disk was in use during the interval.
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Wait Time (ms)
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The average number of milliseconds an I/O request had to wait in the disk queue before being serviced for each disk.
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Service Time (ms)
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The average number of milliseconds an I/O request takes to be serviced once it is removed from the disk queue and processed.
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Read Rate (/s)
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The number of physical reads from the disk per second.
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Write Rate (/s)
|
The number of physical writes from the disk per second.
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Avg Size (kb) Read
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The average size of the physical reads from the disk.
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Avg Size (kb) Write
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The average size of the physical writes from the disk.
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TOTALS
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The totals for each column in the tabular DISK I/O SUMMARY.
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