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title Configure Ubuntu Cluster for SQL Server Availability Group | Microsoft Docs
description
author MikeRayMSFT
ms.author mikeray
manager jhubbard
ms.date 02/09/2017
ms.topic article
ms.prod sql-linux
ms.technology database-engine
ms.assetid dd0d6fb9-df0a-41b9-9f22-9b558b2b2233

Configure Ubuntu Cluster for SQL Server Availability Group

This document explains how to create a two-node availability group cluster for SQL Server on Ubuntu.

Note

At this point, SQL Server's integration with Pacemaker on Linux is not as coupled as with WSFC on Windows. From within SQL, there is no knowledge about the presence of the cluster, all orchestration is outside in and the service is controlled as a standalone instance by Pacemaker. Also, virtual network name is specific to WSFC, there is no equivalent of the same in Pacemaker. It is expected Always On dmvs that query cluster information to return empty rows. You can still create a listener to use it for transparent reconnection after failover, but you will have to manually register the listener name in the DNS server with the IP used to create the virtual IP resource (as explained below).

Note

This is not a production setup. This guide creates an architecture that is for high-level functional testing.

The following sections walk through the steps to set up a failover cluster solution.

Install and configure Pacemaker on each cluster node

[!INCLUDE RHEL-Configure-Pacemaker]

Create a SQL Server login for Pacemaker

[!INCLUDE SLES-Create-SQL-Login]

Open Pacemaker firewall ports

On all nodes open the firewall ports. Open the port for the high-availability service, SQL Server, and the availability group endpoint. The default TCP port for SQL Server is 1433.

sudo ufw allow 2224/tcp
sudo ufw allow 3121/tcp
sudo ufw allow 21064/tcp
sudo ufw allow 5405/udp
		
sudo ufw allow 1433/tcp # Replace with TDS endpoint
sudo ufw allow 5022/tcp # Replace with DATA_MIRRORING endpoint
		
sudo ufw reload

Alternatively, you can just disable the firewall:

sudo ufw disable

Disable STONITH

Run the following command to disable STONITH

sudo pcs property set stonith-enabled=false

Create availability group resource

To create the availability group resource, set properties as follows:

  • clone-max: Number of AG replicas, including primary. For example, if you have one primary and one secondary, set this to 2.
  • clone-node-max: Number of secondaries. For example, if you have one primary and one secondary, set this to 1.

The following script sets these properties.

sudo pcs resource create ag_cluster ocf:mssql:ag ag_name=ag1 \
--master meta master-max=1 master-node-max=1 clone-max=2 clone-node-max=1

Enable monitoring on master

To enable monitoring, run the following commands on one node.

sudo pcs resource op add ag_cluster monitor interval=11s timeout=60s role=Master
sudo pcs resource op add ag_cluster monitor interval=12s timeout=60s role=Slave

Create virtual IP resource

To create the virtual IP address resource, run the following command on one node. Use an available IP address from the network.

sudo pcs resource create virtualip ocf:heartbeat:IPaddr2 ip=<10.128.16.240>

Add colocation constraint

To add colocation constraint, run the following command on one node.

sudo pcs constraint colocation add virtualip ag_cluster-master INFINITY with-rsc-role=Master

Add ordering constraint

The colocation constraint has an implicit ordering constraint. It moves the virtual IP resource before it moves the availability group resource. By default the sequence of events is:

  1. User issues pcs resource move to the availability group master from node1 to node2.
  2. The virtual IP resource stops on node 1.
  3. The virtual IP resource starts on node 2.

    [!NOTE] At this point, the IP address temporarily points to node 2 while node 2 is still a pre-failover secondary.

  4. The availability group master on node 1 is demoted to slave.
  5. The availability group slave on node 2 is promoted to master.

To prevent the IP address from temporarily pointing to the node with the pre-failover secondary, add an ordering constraint.

To add an ordering constraint, run the following command on one node:

sudo pcs constraint order promote ag_cluster-master then start virtualip

Manual failover

Manually failover the availability group with pcs. Do not initiate failover with Transact-SQL.

To manually failover to cluster node2, run the following command.

sudo pcs resource move ag_cluster-master node2 --master

Note

At this time manual failover to an asynchronous replica does not work properly. This will be fixed in a future release.

Next steps

Create SQL Server Availability Group