Which Backup Vendors Offer Immutable, Air-Gapped Backups in 2026

Many ransomware operators go after backups before they go after production. If they can encrypt or delete recovery copies, paying becomes the victim's only option. Immutable, air-gapped backups are the countermeasure: copies that cannot be altered, held somewhere a compromised network cannot reach.

This guide covers what "immutable" and "air-gapped" actually mean, which vendors deliver them and how, and how to evaluate the options against your recovery, compliance, and budget requirements.

Immutable backups are locked against change or deletion for a defined retention period. Once written, the data cannot be encrypted, modified, or erased until the retention window expires, even by someone holding valid administrative credentials.

The enforcement mechanism varies, and the variation matters more than the label. Some vendors use write-once storage or object-lock policies governed by a retention clock. Others enforce immutability through access control, permitting changes only through a secured interface. 

Air-gapped backups are isolated from the production network. A physical air gap means there is no network connection at all, such as a hard drive that sits in storage with no network or internet connectivity. A logical air gap places the copy in a separate account, cloud, or management plane that stolen production credentials cannot reach. 

Almost every vendor in this guide delivers a logical gap. Physical gaps are more secure, but the trade-off is that they slow down recovery speed. It is worth being precise about which one you are buying.

To summarize:

• Immutability stops a backup from being rewritten
• An air gap stops an attacker reaching it at all

Together they underpin the 3-2-1-1-0 backup rule, which adds one immutable or air-gapped copy and a zero-errors recovery standard to the older three-copies, two-media, one-offsite rule.

Backups are the main route out of a ransomware attack. Barracuda's Ransomware Insights Report 2025, based on a Vanson Bourne survey of 2,000 senior security decision-makers across a range of markets, found that 65% of ransomware victims were able to restore their data using backups. 

That is why attackers go after them. In the same report, 19% of victims said they had attackers access and wipe their backups, and a further 19% had shadow copies of files deleted, specifically to make recovery without paying harder. 

Paying the ransom is not a reliable alternative. 32% of surveyed victims paid a ransom, but only 41% of those who paid did not get all of their data back. 

A backup sitting on the production network, reachable with production credentials, is a liability. Pairing immutable backups with air-gap security closes off backups from attackers. That combination is now a baseline expectation in any serious ransomware recovery plan. 

Some key takeaways from the above vendor comparison:

• Immutability is universally offered, but each vendor has slightly different restrictions around stored data, with some allowing access through a secured interface but others requiring support from the vendor.
• Since physical air-gapping is not offered publicly by any vendor, there are different levels of logical and virtual air-gapping available. When evaluating vendors, compare their air-gapping mechanism against security and compliance requirements.
• Access control is crucial; make sure backup vendors support multi-factor authentication (MFA) for admin credentials

Nearly every vendor now claims immutability. The question that separates vendors is narrower: can a holder of valid privileged credentials delete this backup?

Ask it three ways. 

• Can your own administrator shorten the retention lock or delete the repository? 
• Can the vendor's support team do it on request? 
• Does releasing a lock require more than one person?

Start with the enforcement model. Is immutability a retention clock the storage enforces, or an access-control boundary the application enforces? Then establish where the air gap actually sits. A separate account inside the same cloud is a partial gap. A separate provider, or a vendor-held tenant, is a stronger one. A disconnected system is the only complete one.

Then put the privileged credentials question in all three of its forms: what your administrator can do, what the vendor can do, and whether releasing a lock requires two people.

Finally, ask about Recovery Time Actual, meaning the measured time to restore a full workload in a test, rather than the advertised recovery time objective.

Then match the answers to your situation:

• Enterprise IT security teams: tested Recovery Time Actual, malware scanning before restore, isolated recovery testing, and 24/7 incident support.
• Compliance-driven organizations: compliance-mode immutability rather than governance mode, certified storage, audit logging, and chain-of-custody records.
• Microsoft 365-centric organizations: coverage depth across Exchange, SharePoint, OneDrive, Teams, and identity data, with backup storage isolated from the Microsoft 365 environment.
• MSPs: per-user or per-client licensing, centralized multi-tenant management, and fast deployment across customer environments.

Compliance and cyber insurance requirements for air-gapped backups

Regulations such as HIPAA, GDPR, and SEC data-integrity rules do not always use the word immutability, but they require tamper-evident records and verifiable audit trails that immutable backups provide by design.

Cyber insurers have followed suit. Proof of isolated, unalterable backup copies is increasingly a condition of coverage or a factor in premium pricing. Certified storage and clear chain-of-custody logging give compliance teams the documentation auditors and insurers ask for. For instance, Barracuda Cloud-to-Cloud Backup is independently SOC 2 audited annually, and Barracuda Cloud Storage is SSAE Type II certified.

Strengthen your ransomware recovery strategy with Barracuda

Immutable, air-gapped backups are an architecture decision that determines whether you recover on your terms or an attacker's. Barracuda's data protection and backup solutions combine immutable storage, air-gapped cloud copies, and 24/7 ransomware recovery support across physical, virtual, and Microsoft 365 environments. Review your current architecture against the questions in this guide, and confirm your provider's enforcement model, air-gap design, and tested recovery time before the next attack tests them for you.