Deploy a Pacemaker cluster for SQL Server on Linux

Applies to: SQL Server on Linux

This tutorial describes the tasks required to deploy a Linux Pacemaker cluster for a SQL Server Always On availability group (AG) or failover cluster instance (FCI). Unlike the tightly coupled Windows Server / SQL Server stack, you can create a Pacemaker cluster and configure an availability group (AG) on Linux before or after installing SQL Server. You configure the integration and resources for the Pacemaker portion of an AG or FCI deployment after the cluster is configured.

Important

An AG with a cluster type of None doesn't require a Pacemaker cluster and can't be managed by Pacemaker.

Install the high availability add-on and install Pacemaker.
Prepare the nodes for Pacemaker (RHEL and Ubuntu only).
Create the Pacemaker cluster.
Install the SQL Server HA and SQL Server Agent packages.

Note

Starting in SQL Server 2025 (17.x), SUSE Linux Enterprise Server (SLES) isn't supported.

Prerequisites

Install SQL Server on Linux.

Install the high availability add-on

Use the following syntax to install the packages that make up the high availability (HA) add-on for each distribution of Linux.

Register the server using the following syntax. You're prompted for a valid username and password.
```
sudo subscription-manager register
```

List the available pools for registration.

sudo subscription-manager list --available

Run the following command to associate RHEL high availability with the subscription.
```
sudo subscription-manager attach --pool=<PoolID>
```
In this example, PoolId is the pool ID for the high availability subscription from the previous step.

Enable the repository to use the high availability add-on.

sudo subscription-manager repos --enable=rhel-ha-for-rhel-7-server-rpms

Install Pacemaker.

sudo yum install pacemaker pcs fence-agents-all resource-agents

sudo apt-get install pacemaker pcs fence-agents resource-agents

Prepare the nodes for Pacemaker (RHEL and Ubuntu only)

Pacemaker uses a user named hacluster that you create on the distribution. On RHEL and Ubuntu, the HA add-on installation creates this user.

On each server that will serve as a node in the Pacemaker cluster, create the password for a user that the cluster uses. The examples use the name hacluster, but you can use any name. All nodes in the Pacemaker cluster must use the same name and password.
```
sudo passwd hacluster
```
On each node that will be part of the Pacemaker cluster, enable and start the pcsd service with the following commands (RHEL and Ubuntu):
```
sudo systemctl enable pcsd
sudo systemctl start pcsd
```
Then, run the following command to make sure that pcsd starts.
```
sudo systemctl status pcsd
```
Enable the Pacemaker service on each possible node in the Pacemaker cluster.
```
sudo systemctl start pacemaker
```
On Ubuntu, you see an error:
```
pacemaker Default-Start contains no runlevels, aborting.
```
This error is a known issue. Despite the error, enabling the Pacemaker service is successful. This bug will be fixed in a future update.
Next, create and start the Pacemaker cluster. There's one difference between RHEL and Ubuntu at this step. While on both distributions, installing pcs configures a default configuration file for the Pacemaker cluster, on RHEL, running this command removes any existing configuration and creates a new cluster.

Create the Pacemaker cluster

This section describes how to create and configure the cluster for each Linux distribution.

Authorize the nodes:
```
sudo pcs cluster auth <Node1 Node2 ... NodeN> -u hacluster
```
In this example, NodeX is the name of the node.
Create the cluster:
```
sudo pcs cluster setup --name <PMClusterName Nodelist> --start --all --enable
```
In this example, PMClusterName is the name you assign to the Pacemaker cluster, and Nodelist is the list of node names separated by a space.

The process for creating a Pacemaker cluster is different on SLES than it is on RHEL and Ubuntu. The following steps show how to create a cluster with SLES.

Start the cluster configuration process by running the following command on one of the nodes:
```
sudo ha-cluster-init
```
You might be prompted that NTP isn't configured and that no watchdog device is found. This condition is fine for getting the cluster up and running. Watchdog is related to fencing a failed node. If you use SLES's built-in fencing, that fencing is storage-based. You can configure NTP and watchdog later.
You're prompted to configure Corosync. You're prompted for the network address to bind to, as well as the multicast address and port. The network address is the subnet that you're using (for example, 192.191.190.0). You can accept the defaults at every prompt, or change if necessary.
Next, you're prompted to configure SBD, which is the disk-based fencing. You can choose to configure this setting later. If you don't configure SBD, unlike on RHEL and Ubuntu, the process sets stonith-enabled to false by default.
Finally, you're prompted to configure an IP address for administration. This IP address is optional, but functions similar to the IP address for a Windows Server failover cluster (WSFC). It creates an IP address in the cluster to be used for connecting to it via HA Web Konsole (HAWK). This configuration is also optional.
Ensure that the cluster is up and running by issuing:
```
sudo crm status
```
Change the hacluster password with:
```
sudo passwd hacluster
```
If you configured an IP address for administration, you can test it in a browser. This test also checks the password change for hacluster.
On another SLES server that will act as a node of the cluster, run:
```
sudo ha-cluster-join
```
When prompted, enter the name or IP address of the server that you configured as the first node of the cluster in the previous steps. The server is added as a node to the existing cluster.
Verify the node was added:
```
sudo crm status
```
Change the hacluster password:
```
sudo passwd hacluster
```
Repeat Steps 8-11 for all other servers to add to the cluster.

Configuring Ubuntu is similar to RHEL. However, there's one major difference: installing the Pacemaker packages creates a base configuration for the cluster, and enables and starts pcsd. If you try to configure the Pacemaker cluster by following the RHEL instructions exactly, you get an error. To fix this problem, perform the following steps:

Remove the default Pacemaker configuration from each node:
```
sudo pcs cluster destroy
```
Create the cluster. In this example, PMClusterName is the name you assign to the Pacemaker cluster, and Nodelist is the list of node names separated by a space.
```
sudo pcs cluster setup --name <PMClusterName Nodelist> --start --all --enable
```

Install the SQL Server HA and SQL Server Agent packages

Use the following commands to install the SQL Server HA package and SQL Server Agent, if they aren't installed already. If you install the HA package after installing SQL Server, you must restart SQL Server for the change to take effect. These instructions assume that the repositories for the Microsoft packages are already set up, since SQL Server should be installed at this point.

If you don't use SQL Server Agent for log shipping or any other use, you don't need to start or configure it.
The other optional packages for SQL Server on Linux, SQL Server Full-Text Search (mssql-server-fts) and SQL Server Integration Services (mssql-server-is), aren't required for high availability, either for an FCI or an AG.

sudo yum install mssql-server-ha mssql-server-agent
sudo systemctl restart mssql-server

sudo zypper install mssql-server-ha mssql-server-agent
sudo systemctl restart mssql-server

sudo apt-get install mssql-server-ha mssql-server-agent
sudo systemctl restart mssql-server

Next step

In this tutorial, you learned how to deploy a Pacemaker cluster for SQL Server on Linux. You learned how to:

Install the high availability add-on and install Pacemaker.
Prepare the nodes for Pacemaker (RHEL and Ubuntu only).
Create the Pacemaker cluster.
Install the SQL Server HA and SQL Server Agent packages.

To create and configure an availability group for SQL Server on Linux, see:

Create and configure an availability group for SQL Server on Linux.

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Last updated on 2026-01-05