High Availability

Have you ever wondered if your application should be able to work in read-only mode? How important is that question?

MySQL seems to be the most popular database solution for web-based products. Most typical Internet application workloads consist of many reads, with usually few writes. There are exceptions of course – MMO games for instance – but often the number of reads is much bigger then writes. So when your database infrastructure looses its ability to accept writes, either because traditional MySQL replication topology lost its master or Galera cluster lost its quorum, why would you want to the application to declare total …

A question I often hear when customers want to set up a production PXC cluster is: “How many nodes should we use?”

Three nodes is the most common deployment, but when are more nodes needed? They also ask: “Do we always need to use an even number of nodes?”

This is what we’ll clarify in this post.

This is all about quorum

I explained in a previous post that a quorum vote is held each time one node becomes unreachable. With this vote, the remaining nodes will estimate whether it is safe to keep on serving queries. If quorum is not reached, all remaining nodes will set themselves in a state where they cannot process any query (even reads).

To get the right size for you cluster, the only question you should answer is: how many nodes can simultaneously fail while leaving the …

In my previous blog post, I discussed the enhanced performance and scalability delivered by extensions to the multi-threaded data nodes in MySQL Cluster 7.2. In this post, I’ll share best practices on the configuration of data nodes to achieve optimum performance on the latest generations of multi-core, multi-thread CPU designs.

Configuring the Data Nodes

The configuration of data node threads can be managed in two ways via the config.ini file:

- Simply set MaxNoOfExecutionThreads to the appropriate number of threads to be run in the data node, based on the number of threads presented by the processors used in the host or VM.

- Use the new ThreadConfig variable that enables users to configure both the number of each thread type to use and …

Summary

The scalability enhancements delivered by extensions to multi-threaded data nodes enables MySQL Cluster 7.2 to deliver over 8x higher performance than the previous MySQL Cluster 7.1 release on a recent benchmark

What’s New in MySQL Cluster 7.2

MySQL Cluster 7.2 was released as GA (Generally Available) in February 2012, delivering many enhancements to performance on complex queries, new NoSQL Key / Value API, cross-data center replication and ease-of-use. These enhancements are summarized in the Figure below, and detailed in the MySQL Cluster New Features whitepaper

Figure 1: Next Generation Web Services, Cross Data Center Replication and Ease-of-Use

Once of the key enhancements delivered in MySQL …