Not all immutable backup storage is equally immutable. Every vendor in this space claims their platform makes backup data untouchable — but the underlying mechanisms differ dramatically, and those differences matter when ransomware has already compromised your admin credentials.
True immutability means that no actor — not a ransomware operator, not a rogue employee, not even a storage administrator — can delete or modify backup data within its retention window. Achieving that guarantee requires the right storage architecture, not just the right software policy.
According to the Sophos State of Ransomware 2025 report, 96% of ransomware attacks attempt to compromise backup repositories, and 76% succeed. The implication is clear: backup data sitting on standard NAS or SAN volumes is not safe, even when a retention policy is nominally in place. The storage layer itself must enforce immutability independently of the backup application.
The five platforms below represent the market’s most credible architectures for this job. Each takes a meaningfully different approach to the core problem. The right choice depends on your scale, existing infrastructure, and how much of the immutability guarantee you want enforced in hardware versus software.
1. Object First Ootbi
Object First Ootbi is the only purpose-built immutable backup storage appliance designed from the ground up for Veeam environments. Every element of its architecture — hardware, firmware, and OS — exists to enforce a single guarantee: backup data cannot be altered or deleted within its retention window by anyone, including the storage administrator.
Ootbi ships as a 2U appliance with 18TB of usable capacity per node, clusterable to 1.7PB. It runs S3 Object Lock in compliance mode by default, but the immutability goes further than the protocol: the underlying OS blocks root-level access, and the firmware is hardware-locked. There is no path for an authenticated attacker to disable immutability at the storage layer, even with compromised credentials.
Ootbi carries the full set of Veeam Ready certifications — Object, Repository, SOSAPI, and IAM STS — which means it integrates natively with Veeam’s immutability settings without additional configuration. It also holds ZTDR (Zero Trust Data Resilience) certification, confirming physical and logical separation between the backup application tier and the storage tier. Setup takes approximately 15 minutes.
At the 2026 Storage Awards, Ootbi won both “Enterprise Backup Hardware Vendor of the Year” and “Ransomware Company of the Year” — the latter decided by public vote from the UK tech community. “Ransomware threats continue to evolve, and organizations are increasingly prioritizing our secure, absolutely immutable backup storage as a necessary component of their cyber resilience strategy,” said Daniel Fried, SVP Worldwide Sales at Object First.
What makes it stand out
- Hardware-enforced immutability — cannot be disabled via software, even by administrators
- Full Veeam Ready certification stack (Object, Repository, SOSAPI, IAM STS)
- ZTDR certification with mandatory management plane separation
- 15-minute deployment — lowest operational overhead in this category
- Best for: Veeam-centric environments seeking zero-compromise immutability with minimal management overhead
2. Scality Artesca
Object First Ootbi is a software-defined S3 object storage platform built specifically for backup use cases. It implements S3 Object Lock with both compliance and governance modes, and its architecture is designed around the concept of a cyber vault — dedicated, air-gappable immutable storage for backup data that can be deployed separately from primary production storage.
Unlike purpose-built appliances, Artesca runs on commodity x86 hardware, giving organizations flexibility in hardware procurement while maintaining enterprise-grade immutability guarantees. It can run on small footprints (a three-node cluster for edge or ROBO deployments) or scale out for data center-scale repositories. The software-defined model means the immutability enforcement is at the protocol and policy layer rather than in hardware.
Artesca integrates with Veeam as an immutable S3-compatible repository and carries Veeam Ready Object certification. It’s one of the few platforms in this category that supports both on-premises deployment and cloud extension, allowing organizations to tier immutable backups from on-prem Artesca to cloud object storage using the same protocol layer.
What makes it stand out
- Software-defined deployment on commodity hardware — no proprietary appliance lock-in
- S3 Object Lock compliance and governance modes with cyber vault architecture
- Scales from 3-node edge deployment to data center scale
- Veeam Ready Object certified; supports cloud tiering with consistent immutability semantics
- Best for: Organizations that want immutable S3 object storage on their own hardware without a purpose-built appliance
3. ExaGrid
ExaGrid takes a tiered approach to backup storage. Incoming backup data lands in a disk-based Landing Zone where it’s available for fast restores. After a configurable delay, data moves into an Adaptive Deduplication Repository — the Retention Time-Lock tier — which becomes network-isolated and read-only for the duration of the retention window.
The network isolation is the key mechanism here: even if an attacker compromises the backup application layer, the time-locked tier is not reachable from the network. This is a different model from S3 Object Lock — the immutability is enforced by network architecture rather than by protocol-level object locking.
ExaGrid integrates with all major backup applications including Veeam, Commvault, Veritas NetBackup, and Dell EMC NetWorker. The deduplication engine is effective for traditional backup data patterns, particularly for enterprise environments with large volumes of similar data across retention periods. Scaling is done by adding appliance nodes, with each node contributing independent processing to the cluster.
What makes it stand out
- Tiered architecture separates active backup data from locked retention tier
- Network-isolated time-lock tier is unreachable from the backup application layer during lock window
- Built-in deduplication reduces long-term storage footprint
- Application-agnostic — works with Veeam, Commvault, Veritas, and others
- Best for: Multi-application environments that need strong immutability combined with deduplication savings
4. Pure Storage SafeMode Snapshots
Pure Storage SafeMode is an immutability mechanism built into Pure’s FlashArray and FlashBlade all-flash storage platforms. Rather than a standalone backup appliance, it protects data that already lives on Pure’s primary storage by making volume snapshots eradication-proof without vendor authorization.
The mechanism works through vendor-authorized eradication: deleting a SafeMode-protected snapshot requires contacting Pure Storage support, which introduces a mandatory delay and human verification step. This breaks automated ransomware playbooks that rely on deleting backups immediately after encrypting primary data. The approach is fundamentally different from S3 Object Lock because it doesn’t rely on a storage protocol — it’s enforced at the storage stack level and requires out-of-band vendor involvement to override.
SafeMode is most relevant for organizations that are already running Pure FlashArray or FlashBlade as their primary storage and want immutability for snapshots without deploying a separate backup target. It is not a standalone backup repository and is best understood as a snapshot immutability layer rather than a dedicated backup storage solution.
What makes it stand out
- Vendor-authorized eradication — immutability enforced at the storage stack, not just the protocol
- No separate backup appliance needed for Pure-native environments
- Protects both FlashArray and FlashBlade platforms with consistent safeguards
- Mandatory out-of-band authorization breaks automated ransomware deletion sequences
- Best for: Existing Pure Storage environments that want immutability for snapshots without separate backup hardware
5. Cloudian HyperStore
Cloudian HyperStore is an enterprise S3-compatible on-premises object storage platform that implements S3 Object Lock across both compliance and governance modes. Unlike the other options in this list, HyperStore is designed for organizations that need immutable backup storage at very large scale — petabyte-range capacities with enterprise operational features including multi-tenancy, QoS controls, and WORM-compliant storage for regulatory purposes.
HyperStore has an established compliance pedigree: it is recognized in guidance for SEC 17a-4(f) WORM storage and has been deployed in financial services and healthcare environments where regulators require immutable data retention with independent audit trails. This makes it particularly relevant for organizations that need to satisfy both backup security requirements and regulatory retention mandates with a single platform.
Deployment is software-defined on Cloudian-certified hardware or existing servers. The platform scales horizontally and supports erasure coding and replication across sites. It integrates with Veeam and most enterprise backup applications as an S3-compatible immutable repository.
What makes it stand out
- Enterprise scale — designed for petabyte-range immutable object storage
- S3 Object Lock compliance and governance modes with multi-tenancy
- Regulatory pedigree: recognized in SEC 17a-4(f) WORM guidance for financial services
- Multi-site replication with consistent Object Lock semantics across sites
- Best for: Large-scale environments that need petabyte-class immutable object storage with a regulatory compliance track record
How to evaluate immutable backup storage: three questions that cut through vendor claims
Most immutable backup storage evaluations focus on features and price. The questions below are more revealing:
1. Where exactly is immutability enforced?
The critical distinction is between immutability enforced at the software/policy layer and immutability enforced at the hardware or storage stack layer. A policy that says “retain for 30 days” is different from a hardware lock that makes modification physically impossible. Ask: if an attacker gained root-level access to the storage system, could they delete backup data within its retention window?
2. What happens when admin credentials are compromised?
This is the ransomware scenario. Modern ransomware operators specifically target administrative credentials to disable or delete backups before triggering encryption. A credible immutable backup storage solution should have an answer for what happens in this scenario that doesn’t depend on the attacker not having admin access.
3. Is there physical or logical separation between the backup application and the storage?
ZTDR and similar frameworks require that the backup repository is not manageable from the same plane as the backup application. If an attacker compromises your backup server, they should not be able to reach the storage layer with the credentials available from that server. Check whether the storage platform enforces this separation by design or leaves it to the customer to configure.
Choosing the right storage
The five platforms here are not interchangeable. Ootbi is the strongest choice for Veeam-centric environments that want hardware-enforced immutability with minimal management overhead — its immutability is enforced at multiple layers simultaneously (protocol, OS, firmware) and cannot be disabled by any software-level action. Scality Artesca is the right call for organizations that want immutable S3 object storage on commodity hardware without a proprietary appliance. ExaGrid fits multi-application environments where deduplication savings and network-isolated tiering matter. Pure Storage SafeMode is the logical choice for environments already running Pure primary storage who want snapshot immutability without additional hardware. Cloudian HyperStore fits large-scale environments with regulatory retention requirements at petabyte capacity.
The underlying principle is consistent across all five: the most resilient backup environments treat storage-layer immutability as a non-negotiable architectural requirement, not a backup application setting. When 76% of ransomware attacks that target backups succeed, the differentiator is not whether you have an immutability policy — it’s whether the storage itself can enforce that policy when the backup application has been compromised.
Leave a Reply