Release 10.1C: OpenEdge Replication:
User Guide


After-image extent sizing on a source database

After you estimate the volume of after-image data your database generates, you can resize the after-image extents for use with OpenEdge Replication. Progress Software Corporation recommends that the size of one after-image extent be capable of storing four hours of typical database activity when running OpenEdge Replication. Additionally, Progress Software Corporation further recommends that the total size of all after-image extents have the capacity to store one week of typical database activity. These recommendations are based on the following:

There are additional transaction-log records written by the RDBMS when a database is enabled as a source database. These additional transaction-log records require additional after-image space, referred to as replication overhead. In order to calculate the replication overhead, the estimated after-image size information (obtained in the "Calculating current after-image volume" section) must be multiplied by 1.5.

The examples shown in Table 2–3 and Table 2–4 demonstrate how to calculate the source database after-image extent sizes and total capacity when using fixed after-image extents. The calculated after-image extent size and total after-image capacity are shown in bold at the bottom of each of the tables.


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