Score:1

Can a RDS Multi AZ w/one standby be converted to Multi AZ w/two readable standbys?

ge flag

I'm looking at the two AWS RDS options for highly available databases :

  • Multi-AZ with one standby
  • Multi-AZ with two readable standbys

https://aws.amazon.com/rds/features/multi-az/

My understanding is that with Multi-AZ with one standby, you pay for two instances. However, you can only use one instance. When a failure occurs, the other instance takes over.

With the Multi-AZ with two readable standbys option, am I right that we are then talking about a total of 3 instances? A writer instance, and two reader instances (and not a writer + failover writer + two readers)?

If I start out with Multi-AZ with one standby, can this setup be converted to a Multi-AZ with two readable standbys if I down the road find out that I'd like to have a reader?

I could probably add a reader node to the Multi-AZ with one standby, but then I'd miss out on the faster failover time and lower commit latency which comes with the Multi-AZ with two readable standbys.

Tim avatar
gp flag
Tim
Interesting question. The two standby option is very new so not many people will have experience with it. If someone here can't help I might ask AWS Support - though sometimes in AWS it's easiest just to have a play in the console. If there's no direct support you may have to snapshot / recreate your database.
mangohost

Post an answer

Most people don’t grasp that asking a lot of questions unlocks learning and improves interpersonal bonding. In Alison’s studies, for example, though people could accurately recall how many questions had been asked in their conversations, they didn’t intuit the link between questions and liking. Across four studies, in which participants were engaged in conversations themselves or read transcripts of others’ conversations, people tended not to realize that question asking would influence—or had influenced—the level of amity between the conversationalists.