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Title
The I/O screen is different in v7.6 -
Description
I recently converted to SpotLight version 7.6; previously, I was using version 7.1. The I/O screen is quite different from what I had with version 7.1.
Previously, I understood service time of different processes or files in terms of ms/writes or ms/read, as an average over 30 seconds. I still need to know I/O average access time over 30 seconds. However, I see waits/second, ms/wait, total service time expressed as ms/s. May I get an explanation of each quadrant? -
Resolution
The general view is that what the user should be examining in 7.6 is the Latency chart (the top right chart in the Summary tab). This will give the user ms/read and ms/write amongst the many other ways of examining the data. Note the Category dropdown on this page, giving the user a variety of breakdowns.
The help for this chart is as follows (right-click/What’s This or hit F1):LatencyFor the category you have selected at the top of the page, Latency shows the average time delay experienced while the database performs different types of I/O activities.
Values that are consistently high over the displayed period are those most likely to contribute to performance bottlenecks.
• For the Consumer Group, File Type, and Function categories, latency is the average time (in milliseconds) taken to process a physical I/O request.
• For the default Wait Type category, latency is the average time (in milliseconds) taken to process a wait event.
To maximize response time to end users, the latency should remain low – in general a latency below 10ms will give users good response time. As the latency increases, the response time may degrade. This time will vary from database to database – for example in a large batch job – the latency might not be as important as the throughput, but when there is a lot of users on the system, a low latency is important to ensure response time.Details for the selected categoryFor Consumer Groups (Oracle 11g and later), data is derived from V$RSRC_CONSUMER_GROUP, and shows latency for active consumer groups. (Valid only for active resource plans.)
For the File Type category, data is derived from V$IOSTAT_FILE.
For the Function category (Oracle 11g and later), data is derived from V$IOSTAT_FUNCTION, and shows latency for applications or jobs on the database.
The default Wait Type category groups latency according to the types of I/O performed on the database. Spotlight generates the data from information in V$SYSTEM_EVENT.