Overview - Brief Description of Feature

This feature provides support for monitoring terminal cpu, memory, and disk use including utilization tables that track 24 hour (by default) historical min and max utilization.

Problem - What Problem Does the Feature Solve?

A basic requirement of system management tools includes access to instantaneous and historical system resource usage information.  Inclusion of this resource information in InSight's data model consolidates access to this kind of information and allows for easy remote access.  The utilzation tables allow instant access to historical information at any time without having to separately turn on performance monitoring.

Solution - Short Description of How the Feature Works

InSight supports access to instantaneous system resource information with both 'get' and  'event' access.   A client can issue a 'get' to instantly read a value or the client can request that InSight send updated values at intervals appropriate for the value.  InSight queries 4690 for the actual values prior to sending the data to a client.

Access to historical information is available through 'utilization tables.'  The following is a brief overview of a utilization tables:

--  A Utilization Table is a table which records results, over time, of
--  operating system statistics sampling.  When a given Utilization Table is
--  activated, an agent reads information from the operating system at a
--  constant rate (eg 15 seconds - the polling interval).  The agent keeps
--  a list of poll samples corresponding to the past 1 hour.  When it is time
--  to generate an event, update a history row, or respond to a GET request,
--  the agent calculates each Utilization Table row appropriately from the
--  poll sample list.
--
--  Each row in the Utilization Table corresponds to a summary time period.
--  Rows in the table correspond to one of 3 sections:
--
--      Row 1           Poll Interval Row - typically corresponds to the
--                         polling interval.
--      Row 2 - n       Summary Rows - correspond to intervals such
--                         as 'last 1 minute', 'last 5 minutes', etc.
--      Rows n+1 - end  History Rows - These are periodic snapshots of one of
--                         the summary rows.  See a detailed description of
--                         HISTORY ROWS below.