CODEWITHSUNDEEP
mysqlcluster-computing
Pawan
Pawan

Reputation: 529

MySQL cluster data node replacement

I have a MySQL cluster with 2 data storage nodes running from last 2 years.

Just recently I have observed a hardware issue in one of the node (data storage). I may need to replace this node with new one altogether.

It will be great if someone can suggest the best way to do it. I am trying to prevent any data lose during this process. Will it be ok if I do not use same mysql version as installed in other node.

Upvotes: 1

Views: 2375

Answers (1)

Andrew Morgan
Andrew Morgan

Reputation: 570

There should be no problem swapping out your data node while the Cluster is still on-line.

If you want the host running the replacement data node to use the IP address that is currently used by the to-be-replaced server then simply stop that data node (using the ndb_mgm command), configure the new host with that IP address and then start it up (connecting to the existing management node).

If you want the new host to have a different IP address and the data node on the server with the hardware issue is still functional then you can perform the following:

  1. Edit the configi.ini file to change the IP address of the data node being
    migrated
  2. Restart (with the --initial option) all of the management nodes - doesn't cause an outage
  3. Restart the 'healthy' data node (without the --initial option!)
  4. Stop the 'unhealthy' data node
  5. Start the new data node and wait for it to join the Cluster
  6. Restart each API node (mysqld) in sequence

Note that I haven't tested this out and so I'd strongly recommend that you try it out in a non-production environment first (and of course, backup you production database before you do it for real).

It is possible to run nodes on different versions of the software but this is normally only done in the context of an upgrade of the Cluster and so I'd recommend upgrading your Cluster to the latest release (7.2 if possible) before starting the process; if that isn't possible then I'd suggest introducing the new data node on the old release and then perform an upgrade to the new release once everything is back to normal.

For reference, you can see the upgrade compatibility between different Cluster versions at http://dev.mysql.com/doc/refman/5.1/en/mysql-cluster-upgrade-downgrade-compatibility-7.x.html

Regards, Andrew.

Upvotes: 3

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