Release 10.1C: OpenEdge Replication:
User Guide
Configuring transition
For transitioning to operate properly, you must configure it. The following section describes choosing one or two target databases and automatic or manual transition processing.
Choosing one or two target databases
OpenEdge Replication allows for up to two target databases, though only one of the target databases can be used to automatically transition into a normal OpenEdge database. The target database that will automatically transition to a normal OpenEdge database in a failure condition is the first target database whose
[control-agent.agent]
properties in theserver.repl.properties
file havecritical
set to1
andtransition
set toauto
. If you set more than one target database tocrtitical=1
andtransition=auto
, OpenEdge Replication will only recognize the first target database specified in theserver.repl.properties
file for automatic transition. The second database will have to be transitioned manually.The target database you choose as critical is the database you can use as a hot standby should the source database become unavailable. This target database should be on a machine that has reliable TCP/IP connectivity and has the resources for clients to connect to and perform database updates should your source database become unavailable.
Only one target database should be designated to transition. If you transition two target databases and users make updates to both databases, you will not have a single target database with which to resource your source database.
Setting up automatic transition
When the OpenEdge Replication agent loses contact with the OpenEdge Replication server, the agent will wait for a configured amount of time, known as
transition-timeout
, for the server to reconnect. If the OpenEdge Replication server does not reconnect before thetransition-timeout
expires, the target database will be transitioned to a normal database by the agent.For automatic transition to be performed by the OpenEdge Replication agent, the following must be true:
You can use the sample properties file in Figure 3–3 as a guide.
Figure 3–3: Server properties file with automatic transition
As Figure 3–3 shows, the OpenEdge Replication agent,
agent1
, waits for connection from the OpenEdge Replication server for 1200 seconds, or 20 minutes, before it performs transition.Setting up manual transition
With manual transition, when the OpenEdge Replication agent loses contact with the OpenEdge Replication server, it waits indefinitely for a transition to be performed by the DBA. If the OpenEdge Replication server reconnects any time before transition is performed, normal processing resumes.
In order for manual transition to be performed by the OpenEdge Replication agent, the following must be configured:
- The server property
transition
must be set tomanual
.- The control-agent property
critical
can be set to0
, for noncritical.- The server property
transition-timeout
should be set to a reasonable value. Even though this value is not used for manual transition, it should be set in case transition is changed toauto
.The sample properties file in Figure 3–4 can be used as a guide.
Figure 3–4: Server properties file with manual transition
As Figure 3–4 shows, the OpenEdge Replication agent,
agent1
, will wait for connection from the OpenEdge Replication server indefinitely for the DBA to perform transition.Before performing a manual transition, be sure to refer to the "Manually applying after-image extents" section.
To perform transition manually, use the following command:
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