Monitoring I/O by Type

The I/O Type charts enable you to monitor I/O by the types of read and write operations. Small I/Os are requests smaller than 128 KB and are typically single database block I/O operations. Large I/Os are requests greater than or equal to 128 KB. Large I/Os are generated by database operations such as table/index scans, direct data loads, backups, restores, and archiving.

Figure 4-5 Performance Monitoring I/O by Type

Description of "Figure 4-5 Performance Monitoring I/O by Type"

When optimizing for short transaction times, such as in an OLTP environment, monitor latency for small I/Os. High latencies typically indicate that the storage system is a bottleneck.

When optimizing for large queries, such as in a data warehouse, performance depends on the maximum throughput the storage system can achieve rather than the latency of the I/O requests. In this case, monitor the I/O megabytes per second rather than the synchronous single-block I/O latencies.

To monitor I/O by type:

1. Access the Database Home page.

   See "Accessing the Database Home Page" for more information.

2. From the Performance menu, select Performance Home.

   If the Database Login page appears, then log in as a user with administrator privileges. The Performance page appears.

3. In the instance activity area, click I/O tab.

   The I/O Megabytes per Second and I/O Requests per Second graphs appear.

4. For I/O Breakdown, select I/O Type.

   The I/O Megabytes per Second by I/O Type and I/O Requests per Second by I/O Type charts appear.

5. 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.

   The I/O Details page appears.

   You can view real-time or historical data for details on I/O megabytes or I/O requests.