April 12, 2016 at 3:32 pm
Hi,
If I have Server A and Server B and want to use them both like active active sql clusters but with Availability Groups so not true SQL clusters do I need to create a different cluster on each server?
On Server A I have created a failover cluster called clusterA with two nodes Server A and Server B. An availability group has been configured on server A with Server B being the secondary.
Now I want to do the opposite with server B.
Should I create a cluster on Server B?
I hope this makes sense.
Thanks for any help.
April 13, 2016 at 7:32 am
Availability groups have no inherent connection to failover clusters. The most common pattern I know of for installation is to do two standalone installs of SQL on two nodes. These two nodes are in a single Windows cluster, but there is no shared storage and the two instances are independent. An availability group is a collection of one or more databases that two or more instances share. Think mirroring on steroids.
So the simple answer to your question is, install a default instance on both nodes, make them in one Windows cluster, and make two availability groups. Each instance can take one of the two groups as primary. This will be "active/active". If you have a single failover cluster instance, you don't have availability groups, and it would be overkill on the same two node cluster to build a second FCI and then use AGs to duplicate the database. It would work but it would not accomplish anything particularly useful for HA/DR in that configuration.
April 13, 2016 at 8:21 am
Hi,
Thanks very much for your reply. What you suggest is essentially what i have done.
I have configured a number of availability groups on Server A and they are pointing to Server B as the replica. I have now come to create the availability groups on Server B. This is where i began to question myself.
You have reassured me. Thanks very much.
One more question. In a manual fail over scenario once you have done the fail over in Management Studio do you need to do anything in cluster management?
Thanks again.
April 13, 2016 at 9:26 am
Never never never manage AGs from Failover Cluster Administrator. Only in SSMS should you manage them.
April 14, 2016 at 2:23 am
Great. Thanks for pointing that out.
April 14, 2016 at 10:52 am
8adger (4/12/2016)
Hi,If I have Server A and Server B and want to use them both like active active sql clusters but with Availability Groups so not true SQL clusters do I need to create a different cluster on each server?
On Server A I have created a failover cluster called clusterA with two nodes Server A and Server B. An availability group has been configured on server A with Server B being the secondary.
Now I want to do the opposite with server B.
Should I create a cluster on Server B?
I hope this makes sense.
Thanks for any help.
in SQL Server 2014, all servers that are to host a replica that will join an Availability Group, must be members of the same windows server failover cluster.
In SQL server 2016 there are changes afoot that will relax this but right here and now this is the requirement. You can create an Avaiability Group that spans separate clusters but this is only supported for migration purposes as cluster objects cannot failover from one cluster to another
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"Ya can't make an omelette without breaking just a few eggs" 😉
April 14, 2016 at 10:54 am
8adger (4/13/2016)
Hi,Thanks very much for your reply. What you suggest is essentially what i have done.
I have configured a number of availability groups on Server A and they are pointing to Server B as the replica. I have now come to create the availability groups on Server B. This is where i began to question myself.
You have reassured me. Thanks very much.
One more question. In a manual fail over scenario once you have done the fail over in Management Studio do you need to do anything in cluster management?
Thanks again.
All availability group failover and management must be carried out via the primary sql server replica using either TSQL or SSMS
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"Ya can't make an omelette without breaking just a few eggs" 😉
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