Multi mgmd node MySQL cluster
I finally took the time to upgrade my MySQL cluster to 5.11 beta in order to test some new features.
I have some clusters running with 2 ndb_mgmd nodes , but the ones that are scheduled for upgrade only have 1 management node yet.
So todays goal was getting multinode namagement up and running on 5.11 , and test the fresh --nowait feature for ndbd.
Digging back to my older docs told me this would be a 15 minute effort, I'd had to change the config file to have 2 management nodes, restart them. Then change the connection strings for the ndbd's so that they have 2 nodes. Solved.
The first thing I ran into was that on the 2nd node I couldn't connect to ndb_mgmd via ndb_mgm , I could connect to it from a remote machine or while specifying a full connection string with the external ip but not from internally.
Off course this was a fine dns problem as it seemed the machine couldn't do lookups for localhost :)
The second thing I ran into was that even tough I saw 1 connection string in my primary management node it seemed from ndb_mgm that both nodes didn't see eachother, really strange.. I eventually decided to start the ndbd nodes while not changing my configs and suddenly noticed the 2 nodes started communicating. Mikael then confirmed on the mailinglist that this indeed was expected behaviour
Anyhow .. I also tested the --nowait feature which gives you the opportunity to boot only 1 clusternode and start using the database, rather than having to wait till the 2nd node is up and running, and that also works like a charm.