Output from piartool -qs

Command output from piartool -qs lists the following information every five seconds.

Queue size

The Physical File Size shows the current size of the event queue on disk; that is, the file pimapevq.dat or any overflow queues.

The Page Size is the portion of the file that is loaded into memory for faster access.

The event queue is a circular buffer of pages and each page is a circular buffer of events. That is, when a page is full, PI Snapshot Subsystem tries to write into the next page and PI Archive Subsystem reads the pages in the same order they were written.

The Total Data Pages shows the number of pages, obtained by dividing the event queue size by the page size (minus one for the queue header).

Page activity

The Write Page Index shows the page PI Snapshot Subsystem is currently writing to. Similarly, the Read Page Index indicates the page from which PI Archive Subsystem is reading. Under normal conditions, these two numbers are identical. If PI Archive Subsystem is not reading at the same pace that PI Snapshot Subsystem is writing, page shifts will occur and the Total Page Shifts counter will increment. At any time, the Available Pages counter shows how many free pages are left in the current queue.

Queue capacity

PI Snapshot Subsystem maintains the number of Average Events per Page based on the average size of all events. The subsystem uses this average to derive an Estimated Remaining Capacity in number of events. This capacity is also shown by piartool -ss.

Total Bytes Written shows the volume of data that transmitted through the event queue since PI Snapshot Subsystem was last started.

Configure your queue to hold data from several days.

Event rates

Every time PI Snapshot Subsystem sends an event to the archive, the Total Event Writes counter gets incremented. Similarly, when PI Archive Subsystem reads events, the Total Event Reads is incremented. The difference between these counts equals the total events per queue and is shown by the Current Queue Events.

Overflow queues

When the current queue is entirely full, PI Snapshot Subsystem creates additional queue files of the same size. The Overflow Queues and Total Overflow Events counters indicate how many queues exist and how many events they hold. These counts are the same indicated by piartool -ss.

The Current Queue Id shows the sequence number of the primary queue. This is 0 under normal conditions.