Sql-server – Setting up AlwaysONAG in SQL server 2016 on windows 2016

availability-groupshigh-availabilitysql serversql-server-2016

I am going to set up AG's for the very first time, so with little or no experience, please guide me on below understanding:

If i am setting up 4 node AOAG with below scenario:

Node1-NY Data Center – Primary replica

Node2-NY Data Center – Secondary replica

Node1—Node2 Synchronous mode

Node 3 – Michigan Data Center secondary replica acting as DR site with different subnet with ASYNC mode

Node 4 — Readable secondary in NJ data center for reporting purpose using ASYNC mode

Doubts/Questions:

  1. In above Multi Subnet configuration can i still use a different storage across 4 nodes or do i need to use SAN replication as i have read few blogs and confused if that is a requirement for multi site env

  2. What should be ideal Quorum setup? — Can i have that in NJ site as file share witness?

Also if there is better design than above, please suggest as i have never implemented or worked on AOAG before.

RPO/RTO for critical apps varies between 2 hrs to 4 hours

While for mid critical its between a day and 2

I can add up information as needed.

Thanks

Best Answer

This is generally a consulting engagement since there are lots of minutiae. But to answer your techincal questions:

  1. The AG handles the data synchronization process. There is no storage-based replication needed or involved with AGs whether it is local or multi-site.

  2. You can use the NJ site as a FSW, but arguably the best option for multi-subnet in WS2016+ tends to be cloud witness.Figuring out the right witness for quorum needs a bit more informaiton about your infrastructure, which is again, generally a much deeper consulting engagement.

Also, it's not AOAG. Just AG. Always On (which has a space) is just a marketing umbrella term which covers both AGs and FCIs. The ON is not captialized.

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