MySQL High Availability, 2nd Edition

Chapter 6. MySQL Replication for Scale-Out

Joel stood and stretched and figured it was time for a soda. As he walked around his desk, headed to the break room, his boss met him at his door. “Good afternoon, sir.”

“Hey, Joel. We just sold a bunch of licenses for our new applications. The marketing people tell me we can expect to see an increase in load of at least tenfold on the database server.”

Joel raised his eyebrows. He had added a single slave just last week and that had improved the load problem, but not entirely.

“We need to scale out, Joel.”

“Yes, sir. I’ll get right on it.”

Mr. Summerson tapped Joel on the shoulder and smiled, then walked down the hall to his office.

Joel stood still for a few moments as he pondered what “scale out” meant and formed a plan. “I’ve got to do a little more reading,” he mumbled as he headed to the break room.

When the load starts to increase—and if you are running a successful deployment, it is just a matter of when it will start to increase—you can handle it in two ways. The first is to buy larger and more powerful servers to handle the increased load, which is called scaling up, whereas the second is to add more servers to handle the increased load, which is called scaling out. Of these two, scaling out is by far the more popular solution because it usually involves buying a batch of low-cost standard servers and is much more cost-effective.

In addition to handling an increased load, additional servers can support high availability and other business ...