Release 10.1B: Progress Fathom Replication
User Guide


Fathom Replication and after-imaging

Fathom Replication requires that after-imaging (AI) be activated on the source database. The after-imaging feature allows you to recover a database that was damaged when a failure caused the loss of the database or primary recovery (before-image) area. When you enable after-imaging, the database engine writes notes containing a description of all database changes to the after-image logs.

Before you implement Fathom Replication, it is recommended that you calculate, on average, how much after-image volume your database currently generates. You can then use this average to estimate the network bandwidth that establishing replication for the database will require.

After-image data plays the largest part in determining how much bandwidth will be needed. Although exact data volume cannot be accurately calculated, as it depends on the type of transactions within the application and how much activity is going on against the database, it can be estimated if you know the average amount of after-image volume on your system.

The information in this section provides details related to using after-imaging with Fathom Replication and calculating its effects on database volume and network bandwidth. For more general information about database after-imaging, see OpenEdge Data Management: Data Administration .


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