HA configuration between 2 big DC and 1 small

Hello, all!

I’m newbie in FDB, reading documentation, but haven’t clear understand about HA configuration.

We have two big DC (A, B) and one small “management” DC ( C). As I understand, in this configuration we need to build multi-region configuration: region_1 (DC_A), region_2(DC_B + satellite DC_C (one_satellite_single)).

I don’t quite understand the following questions:

  • What the configuration of coordinators we need to build for quorum in two plus one (small) DC config?
  • Am I correct in understanding, that transaction durability will only be local in primary DC (DC_A), because between DC_A and DC_B async mode and local durability defined by parameters of redundancy mode?

Thanks in advance!

In general for multi-DC configurations, I would recommend using 9 coordinators, with no more than 3 in any DC. For your configuration that would mean 3 in each DC. That ensures that you can lose an entire region, and even one machine in a second region, without losing a majority of your coordinators.

In the configuration you specified, transaction durability is only local in the primary DC, and DC_C is not going to be serving any roles besides having coordinators. That could allow you to fail over manually, with data loss, in the event that you lose DC_A, but you wouldn’t be able to automatically fail over.