July 20, 2017 at 3:18 am
Hi all
So we have a standalone SQL server in production that the business have decided they would like to have HA for. Is it possible to set up a windows cluster on this existing box, for use with AlwaysOn? So I'm not talking about shared storage/SQL FCI - just a windows cluster and then an AlwaysOnAg? If so what's the impact? What do I need to think about?
Thanks!
NB
July 20, 2017 at 6:21 am
You can technically set it up on a single-node cluster (but that's kind of pointless). For actual HA you'll need at least one more SQL instance on the same cluster (and since that's two nodes, you'll probably want a file-share witness as well). Once that's all set up you need to enable the feature in SQL Server Configuration Manager before you can use it (and you can't do that until there's a cluster in place).
July 20, 2017 at 5:44 pm
All good info. Definitely use a file share witness, make sure that you have an AD service account running the SQL services before you get started and that it has permissions to that file share path. Make sure that the SQL service account has permission in the OU where your cluster objects reside if you are creating the AG and Listener yourself. If you will use automatic failover and database health detection, make sure you go into the Failover tab on the cluster role and set the retries to something high (like 100 or more) every 1 hour. While this sounds counter intuitive, we had serious problems with the auto failover until we learned to adjust this setting. And lastly, I'm hoping you are doing this on SQL 2016...you definitely want to be on SP1 (I even recommend the CU's) and expect to reboot the machine a couple times.
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July 21, 2017 at 5:24 am
doodlingdba - Thursday, July 20, 2017 3:18 AMHi all
So we have a standalone SQL server in production that the business have decided they would like to have HA for. Is it possible to set up a windows cluster on this existing box, for use with AlwaysOn?
Yes, but as pointed out you'll likely need more than 1 node in the cluster. The one need is fine to get the new WSFC up and running, do you plan to add further nodes?
doodlingdba - Thursday, July 20, 2017 3:18 AM
So I'm not talking about shared storage/SQL FCI - just a windows cluster and then an AlwaysOnAg? If so what's the impact? What do I need to think about?Thanks!
NB
Read this
http://www.sqlservercentral.com/stairway/112556/
Pay attention to geographic node placement and ensure you configure the quorum model appropriately for the number of nodes in the cluster and their placement
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