Monitoring I/O by Function
The I/O Function charts determine I/O usage level by application or job. The component-level statistics give a detailed view of the I/O bandwidth usage, which you can then use in scheduling jobs and I/O provisioning. The component-level statistics fall in the following categories:
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Background type
This category includes ARCH, LGWR, and DBWR.
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Activity
This category includes XDB, Advanced Queuing (AQ), Data Pump, Recovery, and RMAN.
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I/O type
The category includes the following:
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Direct Writes
This write is made by a foreground process and is not from the buffer cache.
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Direct Reads
This read is physical I/O from a data file that bypasses the buffer cache and reads the data block directly into process-private memory.
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Buffer Cache Reads
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Others
This category includes I/Os such as control file I/Os.
To monitor I/O by function:
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Access the Performance page, as explained in "Monitoring User Activity".
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In the instance activity chart, click I/O.
The Latency for Synchronous Single Block Reads, I/O Megabytes per Second, and I/O Requests per Second charts appear.
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For I/O Breakdown, select I/O Function.
The I/O Megabytes per Second by I/O Function and I/O Requests per Second by I/O Function charts appear.
The example in Figure 4-4 shows that a significant amount of I/O is being performed by the log writer. The log writer activity peaked at approximately 600 I/O requests per second.
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Click the largest colored area on the chart or the corresponding function in the legend to drill down to the function with the highest I/O rate.
An I/O Throughput by I/O Function page appears with details about the selected category.
You can view real-time or historical data for details on I/O megabytes or I/O requests.
See Also:
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Oracle Database Concepts to learn about database background processes such as ARCH, LGWR, and DBWR