Database Clusters, Load Balanced?
I read the documentation and it was not clear if the new 3 nodes clusters are load balanced or not. Quote:
Managed Databases can be configured with either 1 or 3 underlying machines, also called nodes. Using 3 nodes provides you with a highly available database cluster, complete with data redundancy and automatic failover. Your data is replicated across every other node in the cluster. If one goes down, any traffic is redirected to the other available nodes. /end-quote
So does a 3 nodes MySQL managed cluster provide better performance by sharing the load across the cluster or is there one main node bearing the load and if it fails the load is transferred?
5 Replies
rdaniels
Linode Staff
✓ Best Answer
@lazeez A three node cluster would include one main node and two redundant nodes. So, to answer your question, it's the latter. This ensures that your application or website is highly available, has limited downtime.
there one main node bearing the load and if it fails the load is transferred
I did some basic testing and the performance of a 3 node Managed Database was on a par with a loadbalanced 3 node Galera MariaDB cluster on the same hardware spec. That doesn't answer your question, but it seemed like there might be load balancing occurring.
So, to answer your question, it's the latter.
With no load balancing, to get the the same current performance, the price is quite high (x5).
Managed Database offering is still in beta. So, there is no charge at this time.
I'm aware and read the SLA. I can't use it for anything other than to test the service for you.
I have MySQL servers already and know how to deal with them so no tests are beneficial to me. I don't have the resources to simulate for a test for what my current system's load is.
Again, when the service is out of beta and available, if the current price structure stays in place, then I won't be using the service. Each DB node you offer is literally more than twice as costly as bare dedicated node. A cluster of three would cost more than 6 times what I pay for a DB server now (self managed linode). If I were to include my replication/reserve server, the price for a cluster would be very close to 6 times my current cost.
Your DB service would be worth the money if, and only if, a cluster is load balanced. Without load balancing it doesn't make sense for my current use case.
Let me know when you add load balancing to DB clusters and then I would definitely consider moving to it.