Re: Change NoOfReplicas & add/forward mysqld

[Mikael Ronström]

Changing from 1 to 2 replicas requires a backup followed by a restore.
The fastest method is to use the backup in NDB and then use ndb_restore
to restore the data from the backup.

To do this would minimum downtime then do the following.
1) Start the new cluster
2) Set up MySQL Cluster Replication to new cluster from old cluster
3) Take a backup in old cluster
4) Restore backup in new cluster
5) Activate slave in new cluster to get the latest changes.
6) Swap over to the new cluster and stop MySQL Cluster Replication
7) Remove old cluster

There is some more detail to this obviously, the manual should help
you there if you want to use this path.

MySQL Cluster Replication is using MySQL Replication to replicate from
a MySQL Cluster to another MySQL Cluster or to another MySQL Server.

With only 1 replica there will be a loss of the last second of updates
before the crash. With 2 replicas there is no data loss when 1 server fails
and the node will automatically get online again once restarted.