Converting a MySQL standalone cluster to a Composite Primary/DR topology using INI configuration

In this blog post, we demonstrate how to convert a single standalone MySQL cluster into a Composite Primary/DR topology running in two data centers.

Our example starting cluster has 5 nodes (1 master and 4 slaves) and uses service name alpha. Our target cluster will have 6 nodes (3 per cluster) in 2 member clusters alpha_east and alpha_west in composite service alpha.

This means that we will reuse the existing service name alpha as the name of the new composite service, and create two new service names, one for each cluster (alpha_east and alpha_west).

Below is an INI file extract example for our starting standalone cluster with 5 nodes:

[defaults]
...
 
[alpha]
connectors=db1,db2,db3,db4,db5
master=db1
members=db1,db2,db3,db4,db5
topology=clustered

To convert the above configuration to a Composite Primary/DR:

1. First you must stop all services on all existing nodes:

   shell> stopall

2. Update tungsten.ini on all nodes.
   Create the two new services and put the correct information into all three stanzas.
   For example, below is an INI file extract example for our target composite cluster with 6 nodes:

   [defaults]
   start-and-report=false
   start=false
   ...
    
   [alpha_east]
   connectors=db1,db2,db3
   master=db1
   members=db1,db2,db3
   topology=clustered
    
   [alpha_west]
   connectors=db4,db6
   master=db4
   members=db4,db5,db6
   topology=clustered
   relay-source=alpha_east
    
   [alpha]
   composite-datasources=alpha_east,alpha_west

3. Invoke the conversion using the tpm command from the software extraction directory:

   shell> tpm query staging
   shell> cd {software_staging_dir_from_tpm_query}
   shell> ./tools/tpm update --replace-release
   shell> rm /opt/cont/tung/cluster-home/conf/cluster/*/datasource/*

4. Finally, start all services on all existing nodes.

   shell> startall

In future articles, we will continue to cover more advanced subjects of interest!

Questions? Contact Continuent