Network Deployment (Distributed operating systems), v8.0 > Set up the application serving environment > Balancing workloads > Replicating data across application servers in a cluster
Migrate servers from multi-broker replication domains to data replication domains
We can migrate multi-broker replication domains to data replication domains. Any multi-broker domains that exist in the application server environment were created with a previous version of the product.
Determine if the application server 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 application servers. 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 application server configuration you are migrating uses HTTP session memory-to-memory replication that is overloaded at the application or web module level, upgrade your dmgr to the current version of the product before you start the migration process.
After you upgrade your dmgr to the latest version of the product, you can only create data replication domains. Any multi-broker domains that you created with a previous version of the product are still functional, however, you cannot use the admin console to create new multi-broker domains or replicators.
The different versions of application servers cannot communicate with each other. When migrating your servers to the current version of the product, keep at least two application servers running on the previous version so that replication remains functional.
Make sure that all of the application servers that are using this multi-broker domain have been migrated to the current version of the product before you start to migrate any multi-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 the product. The remaining servers on the previous version of the product can still communicate with each other, but not with the migrated servers. The migrated servers can also communicate with each other.
- In the admin 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 application server 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 application server 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 application servers 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.
Related
Data replication domains
Data replication
Memory-to-memory topology: Peer-to-peer function
Replicating data across application servers in a cluster