Managing the Object Tracking List

The Object Tracking List (OTL) provides the interface for tracking replicated object changes. It contains information and status for objects that have been resynchronized, are being resynchronized, and still need to be resynchronized. There is one tracking table for SYSBAS and one for each database IASP.

To access the OTL through the Db2® Mirror GUI, choose the Object Tracking List on the left side of the home page and select the Details option to see all the OTL entries.

Figure 1. Accessing the OTL entries
Accessing the OTL entries

The OTL interface allows you to see the OTL for SYSBAS and each database IASP that has been included into the mirror environment. The following figure shows the OTL entries for SYSBAS.

Figure 2. OTL Details page
OTL Details page

For a description of the columns maintained in the OTL, see RESYNC_STATUS view.

Entries are added to the tracking list in two cases:
  • Certain operations use the OTL to perform normal replication. For example:
    • When new objects are replicated due to a Replication Criteria List (RCL) change
    • When a replicated object is created or restored
    • When a non-replicated object is moved or renamed and the resulting object must now be replicated
    • When a spooled file is created or changed in a replicated output queue
  • Replication is suspended (usually due to one node of the mirrored pair being offline or a reclone) or a database IASP is varied off or otherwise unavailable.

    In these cases, an entry is added to the OTL for each object change. Resynchronization will use the tracked entries to bring the objects back in sync when replication resumes.

    When resynchronization occurs, each OTL entry is updated as it is processed so that the status of the resynchronization can be monitored. If an error occurs while processing a specific entry, it will be updated with the error message to help with problem determination.

    Once resynchronization is complete, the OTL entries are retained as historical entries. These may be useful, especially when preparing for a planned outage, to understand how long resynchronization took the last time there was an outage. To see the historical entries from the Db2 Mirror GUI, click on Summary - Historical. This shows groupings of OTL entries and the summarized length of time the resynchronization took to run.

    Figure 3. Summary of historical entries
    Summary of historical entries
Entries are removed from the OTL in several cases:
  • When the OTL is used for normal replication activity, the entries will be deleted unless an error occurs. If an error does occur, the Db2 Mirror object handler that added the entry might handle the error and remove the OTL error entry.
  • If the RCL is modified so a replicated object no longer is replicated, any OTL entries for that object are removed.
  • A reclone will remove all OTL entries including historical entries.
  • From the Details OTL interface, right click to delete individual entries or all entries that have been assigned to the selected group.
    Figure 4. Delete OTL entries using the Db2 Mirror GUI
    Delete OTL entries using the Db2 Mirror GUI
  • The QSYS2.CHANGE_RESYNC_ENTRIES procedure can be used to remove or defer entries. See CHANGE_RESYNC_ENTRIES procedure.