High availability is an important consideration when running workloads on Azure Virtual Machines (VMs). Here are the steps to set up high availability for Azure VMs:
- Create an availability set: An availability set is a logical grouping of VMs that are placed in different update domains and fault domains. Update domains are used to ensure that VMs are not updated or restarted at the same time, while fault domains ensure that VMs are placed in physically separate locations to protect against hardware or network failures. When you create an availability set, you can specify the number of update domains and fault domains you need, depending on your application’s requirements. It is recommended to have at least two VMs in an availability set for high availability.
- Use managed disks: Managed disks provide built-in replication for your VMs, ensuring that your data is highly available. Managed disks are stored on premium storage, which is designed for high availability and low latency. Managed disks automatically replicate data within the same region, across multiple fault domains. This means that if one fault domain experiences an outage, your data remains available in another fault domain. With managed disks, you do not need to configure or manage storage replication yourself.
- Configure load balancing: Azure Load Balancer distributes incoming traffic across multiple VMs, helping to ensure that your application remains available even if one VM fails. You can configure Azure Load Balancer to distribute traffic across your VMs within the same availability set. You can choose from two types of load balancing: Basic and Standard. Basic load balancing is available at no additional cost and provides simple round-robin load balancing. Standard load balancing offers additional features such as session persistence and health probes.
- Use Azure Site Recovery: Azure Site Recovery provides disaster recovery for your VMs, replicating your VMs to a secondary region. If your primary region experiences an outage, you can fail over to the secondary region to keep your applications running. Azure Site Recovery supports both Windows and Linux VMs. When you configure Azure Site Recovery, you create a recovery plan that specifies the sequence of steps to be taken during a failover. Azure Site Recovery continuously replicates your VMs to the secondary region, ensuring that your data is up to date when you need to fail over.
- Use Azure Backup: Azure Backup provides backup and recovery for your VMs, ensuring that you can recover your data in case of a data loss event. Azure Backup provides several options for backup, including file-level backup, application-consistent backup, and snapshot backup. You can configure Azure Backup to back up your VMs to a separate storage account or to a Recovery Services vault. You can choose how often to back up your data and how long to retain backups. Azure Backup provides both full and incremental backups, which can help reduce storage costs.
By following these steps, you can ensure that your Azure VMs are highly available and that your applications remain available even in the event of a failure. It’s important to regularly test your high availability configuration to ensure that it works as expected and to make any necessary adjustments. You should also monitor your VMs and applications to detect any issues before they become critical.