Exam 918 Replication


High Availability Data Replication (HDR) is a method to replicate data from a primary server to another (secondary) server. HDR replicates any logged database from the primary to the secondary server. While the secondary server is considered a duplicate of the primary, it will not contain data from non-logged databases. The database and schemas exist, as DML (Data Manipulation Language) statements are always logged, but any data inserted, updated, or deleted will not be replicated unless the database is logged. HDR insures that the secondary server is always in sync with the primary server. If the primary server fails, the secondary server can be used as a backup until the primary server is available.


Hardware requirements

Both primary and secondary servers must be identical in terms of platform, OS version, memory, CPU, and storage. The servers must support network connections. The amount of disk space allocated to dbspaces for the primary and secondary servers must be equal.

Database requirements

Both onconfig files should be very similar

Connectivity requirements

To set up connectivity between IDS servers on different machines, do the following:

  • Ensure servers are fully trusted
  • Add the appropriate NETTYPE configuration parameter (soctcp or tlitcp), or ensure the sqlhosts file contains a TCP connection for the DBSERVERNAME or DBSERVERALIAS
  • Ensure that both sqlhosts files contain entries for the other server
  • Test connectivity between the two servers. One good method is to use dbaccess > connection > connect. To ensure the servers are fully trusted, do not user a username or password to connect. If this fails, check the error code and debug the connection

Starting and managing

Starting HDR for the first time

To create an HDR pair, you must use an archive from the primary server, then restore it on the secondary server.

Changing server modes and types

Index replication to secondary server

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