Database Replication and Clustering
The VMware Redo Reader extracts information from the Oracle Redo logs and places that information into an internal PLOG format. This contains the raw transactional data. Unlike the Transaction History Log (THL) used by Tungsten Replicator, the format of this information is not fully serialized. The serialization process is performed by the Tungsten Replicator while the data is being translated into the THL format.
The PLOG information is stored within the Tungsten Replicator installation
directory, within a directory named after the corresponding service. For
example, for the service alpha, the data is located in the
plog/alpha/mine/ directory. The
log information in these files is automatically rotated and managed in the
same manner as the THL files.
When processing very large transactions, for example when doing a bulk load or extraction, the information is temporarily serialized to disk. This can introduce additional disk space requirements when incorporating these large transactions into the THL.