Re: Mysql Cluster 7.5 to 7.6 upgrade

[Thomas Nielsen]

Hi Jeff,

A plain restart of both ndb_mgmds should suffice during upgrade. As Mikael already pointed out, you need to first restart both ndb_mgmds, then all your datanodes using --initial, then restart/upgrade all mysqlds (and other ndbapi nodes you may have).

The datanodes *do* need to be restarted with --initial for upgrade to 7.6, and hence the upgrade needs to be a "rolling upgrade". As you are already aware, using --initial will wipe all data on the datanode being restarted. As long as you restart datanodes *one by one*, they recover the wiped data from other node(s) in its nodegroup that should still be running. If you follow this procedure, you do not loose any data.

More details here: https://dev.mysql.com/doc/refman/5.7/en/mysql-cluster-rolling-restart.html

As you are using multiple ndb_mgmds, do note the closing section in the above docs page!

Hope this helps :)

Thomas