The eServGlobal formal Intranet site is based on Drupal and is maintained by MySQL database replication using Drupal's Database Replication module. As described in the About DBFM topic, Document Publishing within the Intranet site is handled by the Database File Manager (dbFM), developed by eServGlobal. Due to dbFMs ability to handle potentially large documents and files, a more pragmatic approach to database replication was required. In response to these specific needs, eservGlobal developed methods and processes required to handle dbFM replication within their Intranet architecture. This help describes the actions required by administrators to complete or verify the configuration of the master and slave servers.
Replication in general is managed using the Database Replication module. This uses MySQL's replication features in a single master - relay - multiple slave configuration. We have also tried circular replication however this was abandoned because replication to all servers is only as fast as the slowest link in the chain, and recovery from a broken link or dead server was more complex than with the more traditional master / slave setup.
While MySQL's replication keeps the majority of database tables in step the dbfm_data table is an exception. dbfm_data contains the compressed data from the files stored in dbFM as blobs (binary large objects). Because these files are often large and could slow the replication process they are dealt with seperately. Their replication uses http and the admin user can control (throttle) the amount of bandwidth used by the process to ensure that the bandwidth used is not excessive bandwidth and does not impact on other processes.