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Is it possible to have an availability group with just one node in it?

The reason I ask is because I am considering a distributed availability group spanning two single node always on availability groups thus getting away from the requirement for a WSFC. The two nodes being several miles apart which may mean a normal availability group may be problematic with data synching.

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  • Thanks yes considered asynchronous but still wondering if the long distance between modes might cause problems Feb 19, 2020 at 23:49
  • I will need to find out how transaction log management (backups, truncation, log shipping etc) works with this setup too as the databases will need to be in full recovery mode. Feb 20, 2020 at 12:35

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To specifically answer your question, yes you can create an availability group on a single node cluster. I tested this with SQL Server 2017, and you can create an AG on a single node cluster using the "New Availability Group" context menu item in SSMS, or with the raw T-SQL. However, you cannot create one using the "New Availability Group Wizard" item as it requires a second replica to be added to progress through the dialogs.

Based on your comments, I would expect that a two-node cluster with asynchronous replication and manual failover is a better solution. There are no real benefits to using a distributed AG in this situation, and the benefit of a regular AG is that you can fail over and fail back as needed. With a distributed AG, failover is possible, but failback is not.

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I thin you can try the Clusterless AG. The read scale availability group was a feature launched from SQL Server 2017 and should help your case.

Note : This is NOT an HA solution.

You can read more about it here : https://techcommunity.microsoft.com/t5/premier-field-engineering/sql-server-2017-read-scale-availability-groups/ba-p/371423

Clusterless AG Setup

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  • Thanks very much that could be the answer however although it says not disaster recovery I am assuming there must be a way to make the replica the live server in the event of a failure? Feb 19, 2020 at 23:48

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