Device Operational Statistics and Adverse Event Information

 

Overview

 

For each device in the terminal, the terminal agent keeps count of i/o operations to the device and counts adverse events that are reported for the device. The counts are kept in what we call “InSight Operational Statistics Table” format. The design intent of tracking this information and how we track it is to enable positive or negative trends to be noticed and to support “check engine” type functionality using very little memory or disk space.

The operational statistics table consists of rows that can be grouped into two groups. The first group consists of 6 rows containing operational statistics for the past hour. Rows in the first section are updated every minute. The second group (rows 7 and above) are “history rows”. History rows are created by periodically making snapshot copies of one of the rows from the first group.

A row in this table includes the following fields: ending date/time of interval, i/o event count, adverse event count.

Row 1 contains counts since the last minute change. Row 2 is for the previous minute. Rows 3 - 6 are previous 5, 15, 30, and 60 minutes respectively.

One of rows 2-6 can be chosen as the base for the history rows. The default is the 60-minute row. History rows snapshots are taken “on the mark” - so the 60 minute row is copied on the hour to history row 7 after rolling down the existing history rows. A fixed maximum number of history rows are kept. The default is 24 history rows.

The adverse event info table keeps track details on the last 10 adverse events. When an adverse event is detected, details are copied to the adverse event info table.

Finally, a word about i/o events and adverse events. In order to make the information as useful as possible, there have been judgments made about which i/o operations to count and which adverse events are “normal” and which are truly adverse. For example, for the 4610 printer, only write events are counted. Reads are actually totally handled in the printer driver -> no work is done in the printer as a result of the read. Similarly, “document not present” errors are not counted as adverse events because these are encountered as part of normal processing.