Have you ever tried to take a backup of your Azure Storage Account? If you did, were you able to actually set up and take backups for your Storage Accounts? I was not lucky enough to set up backups for a Storage Account recently when asked to by Microsoft Support, but I learned a lot in the process. Mainly that you cannot set up backups, either type, for Storage Accounts that have a hierarchical namespace enabled. Most of the Storage Accounts my team uses have that hierarchical namespace enabled, so we aren’t able to take advantage of the Azure backups for the Storage Account, which I find unfortunate. Hopefully this is a gap that will be filled by Microsoft sooner rather than later since it would be nice to have that extra level of data security.
What’s in this post
- Background
- What is a Hierarchical Namespace and Why Use It?
- Storage Account Backup Limitations
- Ramifications of Backups Not Working for Hierarchical Namespace Storage Accounts
- Summary
Background
As with many posts I write, this one is inspired by a recent problem I was dealing with at work, where it looked like something weird was happening with a Storage Account (spoiler: it wasn’t, see my previous post for more details). While working with Microsoft Support, they requested that I take a backup of the Storage Account where our Data Lake resides, then delete the seemingly problematic directory and recreate it from the backup. I never tried something like that, so I was ready to learn how to set up and take backups for Storage Accounts.
I went through all the necessary steps that should have led to making a backup, like setting up a backup vault and creating a policy. But when I got to the step where I need to add the Storage Account in question to the policy, I wasn’t seeing the Storage Account I wanted in the list of items available to backup. When I searched for something that should bring up a handful of accounts, only one item was listed, and it wasn’t what I needed to backup, which was confusing to me. I had to dig more to figure out why I couldn’t add my Storage Account to the backup policy.
What is a Hierarchical Namespace and Why Use It?
The Hierarchical Namespace is a checkbox that you can enable when creating an Azure Storage Account that gives you a true directory system for storing you files, much like File Explorer on your local machine. Without this setting enabled, you may see things that look like folders because there are slashes in the name of the objects, but those will be stored in a flat structure on the account. To improve data retrieval performance, you can enable the Hierarchical Namespace to create true directory structures so that you can work on whole directories at once instead of doing things one-by-one on blobs.
Storage Account Backup Limitations
When I didn’t see my Storage Account in the list of options I could add to my backup policy, I knew something was up. The main documentation from Microsoft that covers how to set up Storage Account backups does not mention at all that there are scenarios where the backups wouldn’t be possible. To find that information, you have to find a separate document which is called the “support matrix” for those backups.
On that page, if you look at the “Vaulted Backup” option, which is what I had set up after following the backup documentation, you will see that “HNS-enabled Storage Accounts are currently not supported. This includes ADLS Gen 2 accounts, accounts using NFS 3.0, and SFTP protocols for blobs.” If you didn’t now better, you might not even know that “HNS-enabled” means Hierarchical Namespace Enabled.
Tip! When writing documentation, always define your acronyms before using them.
On that same support matrix page, if you flip over to the “Operational Backup”, which is the second method of enabling backups on Storage Accounts, you will see that those also don’t support backups for Hierarchical Namespace enabled accounts. At least this note doesn’t use an undefined acronym: “Storage accounts with hierarchical namespace enabled […] aren’t supported.”
Ramifications of Backups Not Working for Hierarchical Namespace Storage Accounts
I believe that this lack of backups for this type of Storage Account is a giant flaw created by Microsoft. They are pushing the use of Storage Accounts as Data Lakes, hence the “Azure Data Lake Storage Gen 2” (ADLS Gen 2) Storage Account settings being heavily marketed. Data Lakes are meant to be a modern way to handle data, yet we are not afforded modern solutions for backing up that data. (Maybe it’s because they’re trying to move everyone to OneLake on Fabric so don’t care about Storage Account data lakes anymore…)
You could argue that Data Lakes should never be a source of data and should be reproducible in the event of a disaster from the true data sources, but I believe that is a backwards mentality for managing any data in 2025. Sure, our data in our Data Lakes could be remade by running pipelines, but then we would lose the change history of the data that resides across the versioned Parquet files in the Storage Account, which is sometimes very helpful for troubleshooting.
With no standard backup solution for Storage Accounts with Hierarchical Namespace enabled, that means customers utilizing the accounts for Data Lakes are left vulnerable to data loss, even if they have geo-redundancy. Cross-region redundancy does not guarantee that the secondary location has the exact same data as the primary at the moment of failover.
My advice for people using hierarchical namespaces on their Storage Accounts is to create your own backup solution if losing those files would critically affect your business if lost. Write the files to two Storage Accounts at once, or something along those lines. I am a naturally cautious person that likes to have backups for backups, so I wouldn’t leave the security of critical files in Microsoft’s hands. In all likelihood, your files will probably be fine for 99.9999999% of the time, but that small chance of data loss may not be one you’re willing to take.
Summary
As of the writing of this post, Microsoft does not provide any method for creating backups of Storage Accounts using the Hierarchical Namespace settings to give directory organization to the account. If you are using this type of Storage Account and are storing business-critical files, create a secondary backup solution for yourself to ensure you won’t be susceptible to data loss you have no control over.
