Introduction

If you’re running SQL Server on an Azure VM with multi-terabyte databases, choosing the right backup strategy is critical. Should you use Azure Backup or native SQL Server backups? As a data platform consultant, I’ve helped many clients navigate this decision. In this article, I’ll share the key pros and cons of each approach to help you make the best choice for your scenario. By the end, you’ll have a clear understanding of when to use Azure Backup vs SQL Backup for your large Azure SQL Server VMs.

Azure Backup Pros

One of the biggest advantages of Azure Backup is its simplicity. With just a few clicks in the Azure portal, you can enable backup for your entire VM, including all its SQL Server databases. Azure Backup will automatically discover the databases and schedule daily full and transaction log backups. You don’t have to write any scripts or manage backup jobs.

Azure Backup also provides central monitoring and alerting through the Azure portal. You can easily check the status of your backups across all VMs and databases, and get alerted if any issues occur. This reduces management overhead compared to monitoring SQL Server backups individually.

Another benefit is that Azure Backup stores your backups in geo-redundant Azure storage, with 99.999999999% durability. Your backups are protected even if an entire Azure region goes down. With native SQL Server backup, you’d have to set up your own geo-redundant storage.

Azure Backup Cons

A major drawback of Azure Backup is its performance impact on large databases. When Azure Backup runs a full database backup, it has to stream all the data over the network to Azure storage. For multi-terabyte databases, this can saturate your VM’s network bandwidth and slow down your SQL Server workload.

Azure Backup also doesn’t give you much control over the backup schedule or settings. You can’t do differential backups, filegroup backups, or compressed backups to reduce backup size and time. You’re limited to daily full and log backups.

Another issue is that restoring a database from Azure Backup can be slow for large databases, since the backup has to be downloaded from Azure storage to your VM over the network. With native SQL backups stored on local VM disks, restores are much faster.

Native SQL Backup Pros

Using SQL Server’s built-in backup capabilities gives you total control and flexibility. You can fully customize your backup strategy, including:

• Scheduling full, differential, and transaction log backups at optimal frequencies
• Backing up only certain filegroups or files
• Compressing backups to save space and speed up backup/restore
• Striping backups across multiple files for better performance
• Encrypting backups for enhanced security

SQL Server backups are also typically faster than Azure Backup, since they can use the full I/O bandwidth of your local VM disks without going over the network. For multi-terabyte databases, this can significantly reduce backup times.

Restores are much quicker too, since the backup files are immediately accessible on the VM’s local disks. You don’t have to wait for the backup to download from Azure storage.

Native SQL Backup Cons

The main drawback of native SQL backups is that you have to manage everything yourself. You need to write and schedule your own backup scripts, monitor the jobs, and test your restores regularly. This requires more time and SQL Server expertise compared to the automated Azure Backup approach.

You also have to provision enough local disk space on your VM to store the backups. With multi-terabyte databases, this can add significant storage costs, whereas Azure Backup uses cheaper Azure storage.

Critically, native SQL backups are not geo-redundant by default. If you store them on your VM’s disks and your Azure region has an outage, you could lose your backups. You’d have to manually copy your backups to another region for geo-redundancy.

Conclusion

So which backup approach should you use for your large Azure SQL Server VMs? If you have multi-terabyte databases and need the fastest possible backup and restore performance, native SQL backups are usually the best choice. They give you the most control and can fully utilize your VM’s I/O bandwidth.

However, if you want a simple, automated backup solution and are willing to trade some performance for convenience, Azure Backup can be a good fit. It’s also the better choice if you need built-in geo-redundancy without having to copy backup files yourself.

Whichever method you choose, be sure to thoroughly test your backups and restores on a regular basis. Having backups is meaningless if you can’t restore them quickly when needed. With careful planning and testing, you can keep your Azure SQL Server VMs protected and stay ready for any disaster scenario.

Feel free to reach out if you have any other questions! I’m always happy to discuss SQL Server backup strategies.