Migrate servers from multi-broker replication domains to data replication domains
You can migrate multi-broker replication domains to data replication domains. Any multi-broker domains that exist in your appserver environment were created with a previous version of WAS.
Determine if the appserver configuration you are migrating:
- Uses an instance of data replication service in peer-to-peer mode or in client/server mode.
Before you begin migrating a client/server mode replication domain, consider if migrating your replication domains might cause a single point of failure. Because you migrate the servers to the new type of replication domain one at a time, you risk a single point of failure if there are 3 or fewer appservers. Before migrating, configure at least 4 servers that use multi-broker replication domains. Perform the following steps to migrate the multi-broker domains to data replication domains:
Dynamic cache replication domains use the peer-to-peer topology.
- Uses HTTP session memory-to-memory replication that is overloaded at the application or web module level.
If the appserver configuration you are migrating uses HTTP session memory-to-memory replication that is overloaded at the application or web module level, upgrade your deployment manager to the current version of WAS before you start the migration process.
Overview
For HTTP session affinity to continue working correctly when migrating V5.x appservers to V6.1 appservers, upgrade all of the Web server plug-ins for WebSphere Application Server to the latest version before upgrading the appservers that perform replication.
After you upgrade your deployment manager to the latest version of WAS, you can only create data replication domains. Any multi-broker domains that you created with a previous release of WAS are still functional, however, you cannot use the console to create new multi-broker domains or replicators.
The different versions of appservers cannot communicate with each other. When migrating your servers to the current version of WebSphere Application Server, keep at least two appservers running on the previous version so that replication remains functional.
Verify all of your appservers that are using this multi-broker domain have been migrated to the current version of WAS before you start to migrate any mulit-broker domains that exist in the configuration.
To migrate the multi-broker domains that exist in the configuration:
Procedure
- Migrate two or more of your existing servers to the current version of WAS. The remaining servers on the previous version of WAS can still communicate with each other, but not with the migrated servers. The migrated servers can also communicate with each other.
- In the console, create an empty data replication domain. Click Environment > Replication domains > New to create an empty data replication domain.
- Add two of your migrated servers to the new data replication domain.
For example, if you are migrated four servers, only add two of them to the new replication domain.
- Configure the two servers as consumers of the replication domain.
Configure the servers as consumers of the replication domain enables them to use the new domain to share data.
- Add some of the clients to the new data replication domain.
Perform this step only if the appserver configuration you are migrating uses an instance of data replication service in client/server mode.
- Configure these clients as consumers of the replication domain.
- Verify that the new data replication domain are successfully sharing data.
Only the servers and clients that are added to the data replication domain and are configured as consumers of this domain can use the data replication domain functions.
- Add the rest of your migrated servers to the new data replication domain.
When the servers can use the new data replication domain to successfully share data, migrate the rest of the servers that are using the multi-broker replication domain to the new data replication domain.
For example, if you are migrated four servers, add the remaining two servers to the new replication domain.
- Configure these servers as consumers of the replication domain.
- Add the rest of the clients to the new data replication domain.
Perform this step only if the appserver configuration you are migrating uses an instance of data replication service in client/server mode.
- Configure these clients as consumers of the replication domain.
- Restart all of the appservers and clients.
- Delete the empty multi-broker replication domain.
What to do next
During this process, you might lose existing sessions. However, the application remains active through the entire process, so users do not experience down time during the migration. Create a new replication domain for each type of consumer. For example, create one replication domain for the session manager and another replication domain for dynamic cache.
Comparison of multi-broker versus data replication domains
Related concepts
Replication
Memory-to-memory topology: Peer-to-peer function
Related tasks
Replicating data across appservers in a cluster