An Event Chronicle stores events in event history data sets. You define how the system manages the data sets using the Advanced tab of the Alarms and Events Properties dialog in DeltaV Explorer. Refer to the online help for a detailed description of the fields. You can also manually manage data sets using the Event Chronicle Administration tool. There are several types of event history data sets:
Active data set - contains the most recent event records for the associated Event Chronicle. There is one active event history data set in each enabled Event Chronicle. The system allocates a user-specified disk space for the active data set. When the active data set reaches the target size, the system copies the oldest event records to the current data set, and then deletes them from the active data set. You can configure the Alarms and Events properties so that events of a certain age are copied to the current data set before the active data set reaches its target size by completing the following steps:
In the Age for Copying Events to Current History Data Set field, specify a number of hours after which events are copied from the active data set to the current history data set.
Specify a value between 100 MB and 4,000 MB in the Current Event History Data Set Total Storage Target field.
This causes the system to create current history data sets as needed.
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After you complete these steps, events are copied from the active data set to the current data set when they reach the target age, but are not deleted from the active data set until it reaches its target size. This creates some replication between the active and current data sets, but minimizes any risk of losing event records. The online help for the Alarms and Events Properties dialog provides more reference information about the fields.
By default, Process History View connects to the active event history data set for a particular Event Chronicle. When connected to the active data set, Process History View includes event records that have been copied to a current data set, but have not yet been deleted from the active data set.
Current data sets - contain events that the system has copied from the active data set. Current data sets enable you to organize event records into manageable chunks for storage on off-line media. You define the rules that the system uses to creates data sets. Specifically you can set a target size and a calendar period for creating a new data set. For example, you might configure a data set to be approximately the size of a CD for convenient optical storage. Or, you might configure the system to create a data set at the end of each week. The system deletes the oldest data sets when the data sets reach a total target size. You can configure the system to export the data set to another directory or workstation for archival before it is deleted.
Extended data sets - have been created from exported event history data sets. You create an extended data set using the Event Chronicle Administration tool. Refer to the administration tool help for details.
The default time zone reference for an event history data set is UTC, which is the same as Greenwich Mean Time (GMT).
Process History View and the Batch Historian can view event history data sets.