Configure an Azure fence agent or STONITH Block Device (SBD)

To configure an Azure fence agent or STONITH (Shoot The Other Node In The Head) Block Device for your SAP workloads, you can follow the steps outlined below.

1. Understand the Need for a Fence Agent or STONITH Block Device

In a high-availability SAP environment, it is crucial to have a mechanism that can reliably and automatically determine the availability of the nodes. A fence agent or STONITH Block Device is used to fence off unresponsive or failed nodes, ensuring the integrity of the cluster and preventing resource corruption or data loss.

2. Choose a Suitable Fence Agent or STONITH Block Device

Azure provides several options for implementing a fence agent or STONITH Block Device. One popular choice is to use the Azure Fencing Agent, which leverages the Azure API to power off and restart virtual machines (VMs). Another option is to use an Azure Watchdog Timer in combination with the SBD.

3. Configure the Azure Fencing Agent

To configure the Azure Fencing Agent, you need to install the fencing agent on each node participating in the cluster. You can do this by executing the following commands on each node:

sudo apt-get update
sudo apt-get -y install sbd

Once installed, you can configure the fencing agent by creating or modifying the agent configuration file, located at /etc/sbd/sbd.conf. The file should contain the necessary information to authenticate with the Azure API, such as the subscription ID, tenant ID, client ID, and client secret.

4. Configure the STONITH Block Device (SBD)

In addition to the Azure Fencing Agent, you also need to configure the STONITH Block Device (SBD) to work with the fencing agent. The SBD is a shared disk device that acts as a witness to determine the availability of the nodes.

To configure the SBD, you need to create an SBD device on each participating node using the following command:

sbd -d /dev/sdb create

Replace /dev/sdb with the appropriate device name for your environment. You should repeat this command on each node.

5. Configure the Resource Manager

In order for the fence agent or STONITH Block Device to work correctly, you need to configure the resource manager to use the configured fencing agent and SBD. This step involves modifying the cluster resource configuration file or the High Availability Resource Manager (HARM) configuration file.

In the configuration file, specify the path to the fencing agent binary and the SBD device. For example:

stonith_agent = /usr/sbin/fence_azure_arm
sbd_device = /dev/sdb

6. Test the Fencing Setup

After configuring the fence agent or STONITH Block Device, it is essential to test the setup to ensure its effectiveness. You can use a cluster management tool like Pacemaker to simulate a failure scenario and verify if the fence agent or SBD successfully fences off the unresponsive node.

7. Monitor and Maintain the Fencing Setup

Regular monitoring and maintenance of the fence agent or STONITH Block Device is crucial to ensure continuous availability of your SAP environment. Monitor the cluster status, review logs for any error messages, and perform routine checks to ensure proper functioning of the fencing setup.

By following these steps, you can configure an Azure fence agent or STONITH Block Device for your SAP workloads. This will help ensure the availability and integrity of your SAP environment, minimizing downtime and protecting your critical business operations.