Caché Monitoring Guide - InterSystems Documentation

11
Caché History Monitor
The History Monitor maintains an historical database of performance and system usage metrics. Its primary purposes are
to:
• Provide a performance baseline and help with analysis of performance issues.
• Help analyze system usage over time for capacity planning.
This database is defined in the SYS.History class package and kept in the %SYS namespace. All of the details of the database
structure are published there and the data is accessible through SQL or the normal persistent object access. The class documentation
in SYS.History also contains descriptions of all the individual properties, methods and queries that are available.
The data is generally organized into performance (see SYS.History.Performance) and system usage (see
SYS.History.SystemUsage) data. The performance metrics are intended to be sampled at short intervals (by default, 30
seconds), and the system usage data at slightly longer intervals (by default, 5 minutes). At the beginning of each day, the
individual interval samples are summarized into hourly and daily tables as averages, maximums, minimums, standard
deviation, medians and totals. You can select which, if any, of the summary functions are kept for each metric class. The
interval and hourly data may be purged automatically after a defined number of days (by default, seven (7) days and 60
days, respectively); the daily summary is intended for long-term analysis and can be purged manually.
To begin collecting data, use the ^%MONAPPMGR utility to activate the %Monitor.System.HistoryPerf and/or
%Monitor.System.HistorySys classes; for more information, see Collecting Data in this chapter.
This chapter contains the following sections:
• Base Metrics
• Collecting Data
• Summaries
• Accessing the Data
11.1 Base Metrics
All of the collected metrics are defined in four %SerialObject classes in SYS.History. These same classes are used as the
basis for the Interval, Hourly, and Daily databases, so all of the properties are defined as %Numeric types to allow for
decimal values in the summaries.
The performance related metrics are defined in:
Caché Monitoring Guide 97