The term materialization refers to the process of copying the contents of one database (the source) to another (the target), so that both databases contain identical data. This is the prerequisite condition (or starting point) for any system that provides continuous data replication, including the Mirror Activator system.
Materialization always replaces existing data (if any) in the target database with the data in the source database. Therefore, any process that copies only the differences between the source data and the target data (for example, the rs_subcmp utility, or an “incremental replication”) is not materialization.
Some materialization techniques copy all of the source data to the target, but for only part of the source database (for example, subscription materialization in Replication Server). Such techniques are not well suited for databases in the Mirror Activator system.
The Mirror Activator system is intended to replicate a complete database, with a one-to-one relationship between each object in one primary database and each object in one standby database. Because the Mirror Activator system relies on mirror log devices, which are exact copies of the primary database log devices, a device-level database materialization technique works best with the Mirror Activator system.
Although there are other techniques you could use to materialize a database, Sybase recommends snapshot materialization, using the disk replication system to capture a snapshot (or point-in-time copy) of all source database data and log devices, and then send the snapshot to corresponding devices at the target database site.
Snapshot materialization allows you to take advantage of your disk replication system’s facilities to simplify the materialization process, and to reduce the time required for a complete database materialization.
The Mirror Activator system setup procedures in Chapter 2, “Setup and Configuration,” and the failover and failback procedures in Appendix B, “Failover and Failback with Mirror Activator,” are based on using the snapshot materialization technique.
Snapshot materialization requires the primary database
to be quiesced. To minimize primary database downtime, refer to
the appropriate task checklist in the following sections and plan
your materialization procedures carefully.
