Span Tracking

Tracking is the process of extracting only completed changes from a DMSII audit file and then updating the secondary database with those changes. To accomplish the tracking of changes from the host DMSII database to a secondary database, Span uses the audit files created by DMSII. The audit files contain information about which records have been modified, deleted, or added.

You can determine how “up-to-date” your secondary database is by how often you close the DMSII audit files and run Span. For example, you can close the audit file every hour, every day, or even every week, depending on how crucial current information is. If you do not explicitly close the audit file, the Accessroutines close it when the audit file reaches the size specified in the DASDL. If you use the DBEngine parameter setting READ ACTIVE AUDIT = TRUE, Span can process the entire audit trail up to the last quiet point. Since a new audit file is opened as soon as an old one is closed, you can take the closed audit file and immediately begin the updating on the secondary database. Of prime importance is that the secondary database know its exact position in the audit trail.

For information on automating this process, see Automating Span Processing. For information on controlling when audit files close, see DATABridge Utilities.

When updating the secondary database, any of the following issues can arise:

  • Audit position
  • Replicating additional data sets
  • DMSII rollback or rebuilding
  • DMSII reorganizations

Audit Position

Each secondary database must record the current audit position for each data set. (DATABridge provides this information at the end of each transaction group.) If the secondary database is rolled back or reloaded from a dump, the audit position of the secondary database can be rolled back to an audit position prior to the database rollback or reload. Tracking then starts at the rolled back audit position so that the data records on the secondary database are in sync with the actual data records.

Replicating Additional Data Sets

If you want to replicate data sets that you did not include in previous runs of Span, you must uncomment the appropriate entry in the Span parameter file so that Span replicates the added structures as well.

DMSII Rollback or Rebuilding

Before you perform a rollback or reload, see Normal Recovery from a Rollback.

DMSII Reorganizations

Before you perform a reorganization, see DMSII Reorganizations.