How data initially replicates

HDR secondary and RS secondary servers use storage-space backups and logical-log backups (both those backed up to tape and those on disk) to perform an initial replication of the data on the primary database server to the secondary database server.

SD secondary servers do not require a backup and restore from the primary server because SD secondary servers share the same disks as the primary.

To replicate data:

  1. Install user-defined types, user-defined routines, and DataBlade modules on both database servers.
  2. Register user-defined types, user-defined routines, and DataBlade modules on the primary database server only.
  3. To synchronize the data managed by the two database servers, create a level-0 backup of all the storage spaces on the primary database server.
  4. Restore all the storage spaces from the backup on the secondary database server in the data-replication pair.

    The secondary database server that you restored from a storage-space backup in the previous step then reads all the logical-log records generated since that backup from the primary database server.

    The database server reads the logical-log records first from any backed-up logical-log files that are no longer on disk and then from any logical-log files on disk.

For detailed instructions about replicating data, see Starting HDR for the First Time. The IBM® Informix® Backup and Restore Guide explains how to start replication using ON-Bar.

You must perform the initial backup with a storage-space backup. You cannot use data-migration utilities such as onload and onunload to replicate data because the physical page layout of tables on each database server must be identical in order for data replication to work.


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