Understand the scope and freshness of Adaptive Server data in Sybase Control Center.
Each Adaptive Server statistic presented in Sybase Control Center
has a scope:
- Delta – the number of occurrences since the last screen refresh. For example, the user log cache statistics on the Transactions screen are delta values.
- Rate – the number of occurrences over the given period of time. Device I/O is given as a rate.
- Percentage or ratio – an amount, number, or rate stated as a proportion to a whole. Percentage statistics include CPU utilization, space usage on devices and segments, and cache hit rates. Ratios include cache volatility.
- Count – a simple value; for example, the size of a database or cache in megabytes, or the number of partitions in a cache.
- Cumulative – the number of occurrences since Adaptive Server started, or since the counter wrapped. On the Processes screen, you can set the Top 5 User Processes chart to display the five processes that use the most CPU, disk I/O, or network resources as rates or as cumulative values.
Note: When a server has been running for a long time, its statistical counters can wrap, which means they restart from zero. This most often affects cumulative statistics. Information about when or how many times a counter has wrapped is not available.
Most Adaptive Server statistics not otherwise labeled are presented as deltas since the last screen refresh; rates, percentages, and cumulative numbers are labeled as such.
Sybase Control Center displays statistics promptly. However, there are several factors that affect the freshness of the data on the screens:
- The screen refresh interval, which you can set on the Settings screen
- The collection repeat interval, which you can set in the scheduler for each Adaptive Server collection
- Network latency
For more information about interpreting Adaptive Server statistics, see:
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Adaptive Server Performance and Tuning Series: Improving Performance with Statistical Analysis
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Adaptive Server Performance and Tuning Series: Monitoring Adaptive Server with sp_sysmon
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Adaptive Server Performance and Tuning Series: Basics