3

Environment

Windows: 2012 R2 Standard
SQL: SQL 2014 Enterprise Edition
Setup: Two Node Windows Failover cluster with SAN

Changes:

We want to introduce Availability Group to the instance by adding a second SQL instance running at a DR site. It will be Virtual server with attached drive. For Clarity, we will call SQL instance running on two node cluster with SAN as S1 and second SQL instance at DR site as S2

Questions:

  1. Can we create AG groups after Adding S2 to S1 cluster? In the event of S1 failure and it failsover to Node 2, would AGs failover to S2 instance?

  2. Start fresh by creating two instances on new servers setup with AG and then migrate DBs to them?

  3. Licensing - Do we have to pay licensing for both Primary and Secondary instance even though everything will be running on Primary and will failover in the event if Primary goes downs?

Thanks!

5

For your first question, yes you can use the same environment (Windows: 2012 R2 Standard and SQL 2014 Enterprise Edition) but the configuration should be changed. During failover clustering, primary and secondary servers shares the same resources or drives, this didn’t work for Always on configuration, and both primary and secondary replicas has to have their own drives.

For your second question, it depends on your preference and available resources, if you think that it’s easy just to reset drives on both servers and change configuration you could do that. If you have sufficient resources, space in SAN and feels more confident to start a fresh install you might chose the second option.

Concerning about the licensing. Assuming you are planning to use secondary node only for disaster recovery or short maintenance time, you need licensing only for a primary node. However, if you are planning to query from secondary node, you are also required a license for the secondary node too.

  • 1
    Thanks for the answer... I just realized that I missed one more piece... We are going to keep the two node cluster with SAN running one instance of SQL 2014 and then create a second standalone server with disk and SQL 2014 Enterprise. Then introduce AG Groups... Would that work? in the event of failure of primary (two node cluster), would AG failover to the standalone server? – Rizwan Aug 24 '16 at 15:05
  • 2
    No you cannot do that, to configure Always on availability group first you have to setup the cluster which means the secondary node have to be part of the cluster. I am not sure why you want to set up that way but from your question it seems you are thinking to be safer in case your nimble storage failed, if that is the case (which is a very wise consideration), you could still make one of your node a physical server (on disk) and the other on your SAN and configure the cluster. N.B but both nodes have to be part of the cluster. – Hailegziabher Dechassa Aug 24 '16 at 15:22
  • Good point... this is my last question... for clarity I will call instance running on two node cluster with SAN as S1 and standalone instance with its own disk as S2. If we add S2 to S1 cluster, and create AG groups, would it work then? If so in the event of S1 failsover to its secondary node, would AG failover to S2 and come online? – Rizwan Aug 24 '16 at 15:30
  • 2
    When you say standalone if it is to refer standalone sql server installation yes that is what it supposed to be and it will work as long as it part of the cluster. In this case you are creating 3 nodes failover cluster and the licensing issue will be different. Microsoft only allows 1 secondary or disaster recovery node per license which means for 3 node failover cluster you might have to buy 2 licenses but it is possible to get additional node to your cluster – Hailegziabher Dechassa Aug 24 '16 at 15:42

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.