----- On 12 Jun, 2015, at 6:36 PM, Dan Storm st...@err0r.dk wrote:
> Hello. > > I just saw this YouTube video: https://www.youtube.com/watch?v=hYSGsgIyshs > It was really informative and it seems like a simple and easy setup. > > Now, I have a few questions which is regarding maintaining a Galera Cluster, > which I hope to get some answers on. > > 1. A cluster should have an odd number of nodes to avoid brain split. Split brain is avoided with 3+ nodes. You won't get split brain with even nodes as the quorum is 1/2 + 1 nodes. i.e. It does mean 1/2 the nodes can't form a quorum. > In case I > hit the wall with insufficient disk space and I need to scale up my servers, > which steps would be the appropriate? My initial thoughts would be taking down > one node at a time and add a larger node, what for it to have replicated from > the other nodes. > Would the - now even numbered of nodes - handle this? Bit vague. Stick to your even (>2) nodes. > And what will have when I > do this to the bootstrapped server (the one the others connects to)? same as any cluster initialisation > 2. According to the video, a slave replication of the cluster would be a way > of > securing my data in case of disaster. Would creating dumps regularly not > suffice? And secondly, in case of hardware failure on one of the nodes, > bringing in a new node (probably asking the same as before) would hopefully > just replicate the data when it joins again? Look up the important conceptual difference between backup and DR. Make sure what you have meets your requirements for doing a restore (related to backup) in a workable time covering the business requirements. Backup covers things like dumb user did a DELETE without a where clause, SQL injection and general data corruption that will affect all nodes. The DR recovery mechanism (hardware failure etc... ) covers your calculated business and technical risks. Hint, you many need more that one mechanism. -- -- Daniel Black, Engineer @ Open Query (http://openquery.com.au) Remote expertise & maintenance for MySQL/MariaDB server environments. _______________________________________________ Mailing list: https://launchpad.net/~maria-discuss Post to : maria-discuss@lists.launchpad.net Unsubscribe : https://launchpad.net/~maria-discuss More help : https://help.launchpad.net/ListHelp
