Immutable Storage in 2025: 3 Deployment Models and Top 7 Use Cases

What Is Immutable Storage? 

Immutable storage refers to a type of data storage where stored information cannot be modified, deleted, or altered after it’s initially written. This ensures data integrity and provides a secure way to store important information, especially for regulatory compliance, ransomware protection, and preventing accidental data loss.

Key characteristics of immutable storage include:

• Unchangeable: Data written to immutable storage cannot be modified, deleted, or overwritten.
• Data integrity: This feature ensures that the stored data remains in its original state, preventing corruption or unauthorized changes.
• Compliance and security: Immutable storage is crucial for meeting regulatory requirements and protecting data from threats like ransomware.
• Ransomware protection: By preventing data from being modified or deleted, immutable storage ensures that a clean, unaltered copy of data is available for recovery in case of a ransomware attack, eliminating the need to pay the ransom.
• Backup solution: Immutable storage is often used as part of a comprehensive backup strategy, creating a secure and reliable backup copy of critical data.
• Long-term preservation: It can be used to store data that needs to be preserved for a long period, such as audit logs or legal documents.

How it works:

• WORM technology: This technology allows data to be written once but read multiple times, preventing any modifications after the initial write.
• Retention policies: These ensure that data remains immutable for a specified time frame.
• Metadata and auditing: Stored data has details recorded to enable tracking and auditing.
• Software-defined storage: Immutability policies are enforced through software, ensuring that certain storage locations or data types cannot be altered or deleted.
• Encryption: Immutable storage systems often incorporate encryption to further secure the data at rest and during backups.
• Data deletion: Constraints are lifted at the end of the retention policy, making the data mutable and enabling deletion.
• Versioning and snapshots: In some cases, multiple versions of the same data can be stored.

This is part of a series of articles about data backup

In this article:

• Immutable Storage: Benefits, Types, and Uses
• What Is Immutable Storage?
• The Benefits of Immutable Storage
• Types of Immutable Storage
• How Does Immutable Storage Work?
• Immutable Storage and Object Lock
• Immutable Storage for Ransomware Protection
• Limitations of Immutable Storage
• Data Protection and Privacy with Cloudian HyperStore

How Does Immutable Storage Work?

Immutable storage uses a combination of hardware and software mechanisms to ensure that data, once written, cannot be altered or deleted. This usually involves the following technology components:

• Write Once, Read Many (WORM): In immutable storage, data is written once and can be read multiple times. Once the data is stored, it cannot be modified, overwritten, or deleted within the defined immutability period.
• Retention Policies: Immutable storage systems allow administrators to set retention policies that define how long data should remain immutable. These policies can be time-based (e.g., retain data for 5 years) or event-based (e.g., retain data until a specific event occurs, such as the completion of a project).
• Metadata and Auditing: When data is written to immutable storage, metadata is created to track the data’s origin, timestamp, and other relevant information. This metadata is also immutable and cannot be altered. Auditing mechanisms keep a record of all data access and attempted modifications for security and compliance purposes.
• Software-Defined Storage: Immutable storage systems employ various security measures to protect data from unauthorized access and tampering. These measures may include encryption, access controls, and physical security of the storage devices.
• Encryption: While data is in storage, various encryption mechanisms ensure that it is secure so that it cannot be accessed, modified, or deleted by unauthorized parties. Some immutable storage systems also provide in-transit encryption to secure the data during retrieval.
• Data Deletion: Once the specified retention period expires or the defined conditions are met, the immutability constraints are lifted, and the data can be deleted. This deletion process is controlled and audited to ensure compliance with data retention policies.
• Versioning and Snapshots: Some immutable storage systems support versioning, allowing multiple versions of the same data to be stored. Each version is immutable, and users can access and recover specific versions as needed. Snapshots capture the state of data at a particular point in time, providing a consistent and immutable copy for backup or recovery purposes.

Traditional Storage vs. Immutable Storage vs. Immutable Backups: What Is the Difference?

Traditional storage allows data to be modified or deleted at any time, provided the user has the required permissions. This flexibility is useful for day-to-day operations, but it also increases the risk of accidental overwrites, unauthorized changes, or malicious tampering. Backups in traditional systems can also be altered or removed, making them vulnerable during cyberattacks such as ransomware incidents.

Immutable storage removes this flexibility during the defined retention period. Once data is written, it is locked against modification or deletion, regardless of user permissions. This ensures that even if an account or system is compromised, the stored data remains unchanged until the retention policy ends. The trade-off is reduced operational flexibility, but the benefit is stronger data integrity and compliance with strict regulatory standards.

Immutable backups specifically describe secondary copies of data intended for recovery purposes, which are stored on systems featuring immutability capabilities. These backups are designed to resist unauthorized changes or deletions, especially ransomware encryption attempts, significantly enhancing recovery reliability and speed after cybersecurity incidents.

While traditional storage is best for frequently changing operational data, immutable storage is ideal for preserving critical records, meeting audit requirements, and ensuring reliable recovery in the event of data corruption or cyberattacks. Immutable backups use immutable storage technology to protect backups from threats and improve their resilience.

The Benefits of Immutable Storage 

Using immutable storage can:

• Bolster cybersecurity: Preventing data from being altered or deleted by unauthorized entities. This helps in defending against ransomware attacks where malware attempts to encrypt data. The hacker then demands a ransom to make it accessible. With immutable storage, data remains intact, allowing organizations to maintain secure backups.
• Prevent human error: Accidental deletions or incorrect data modifications are common causes of data loss. Immutable storage prevents these errors from becoming catastrophic by ensuring data cannot be altered or deleted as long as the immutability policy remains in effect.
• Ensure regulatory compliance: Regulations such as HIPAA, GDPR, and SOQ impose strict rules on how data should be managed and protected. They mandate the retention and preservation of data for extended periods. Immutable storage solutions help organizations comply with these regulations by providing a secure method that prevents data tampering and deletion, supporting audit processes by ensuring data remains unchanged over time.

Related content: Read our guide to storage management

3 Deployment Models for Immutable Storage

Here are three common ways immutable storage is deployed for use by organizations.

1. On-Premises

Deployed in the organization’s local data center, these solutions provide full control over the storage infrastructure, useful for organizations with stringent security needs. On-premises immutable storage systems can be tailored to specific requirements and integrate with existing security protocols to protect against data tampering. They typically offer higher performance levels and lower latency compared to cloud-based alternatives.

2. Air-Gapped

Air-gapping refers to the practice of isolating data storage systems from other networks, particularly the internet, to prevent unauthorized access. For immutable storage, air-gapping can provide an additional security layer by physically distancing backup data from the production environment which is susceptible to attacks.

3. Cloud-Based

Cloud-based immutable storage involves leveraging a third-party cloud provider to manage immutable data storage. Commonly provided by major providers such as AWS, Azure, and Google Cloud, these solutions enable organizations sufficient control over data retention periods, immutability policies, and access permissions without needing to operate and maintain physical hardware.

However, organizations using cloud-based immutable storage must carefully select trusted providers, scrutinize service-level agreements (SLAs), and clearly understand provider responsibilities to ensure data protection and compliance requirements are consistently met.

7 Common Use Cases for Immutable Storage Solutions

Immutable storage is used wherever long-term data integrity is critical and where the cost of data alteration or loss is high. Its applications span compliance, security, and operational resilience.

Key use cases include:

1. Regulatory recordkeeping – Financial, healthcare, and legal sectors often need to preserve records in their original state for years to comply with regulations such as SEC Rule 17a-4, HIPAA, and GDPR.
2. Ransomware-resilient backups – Immutable backups ensure recovery is possible even if production systems are encrypted or corrupted during a cyberattack.
3. Audit and forensics – Immutable logs, transaction records, and system snapshots support forensic investigations by guaranteeing evidence remains untampered.
4. Intellectual property protection – Design files, research data, and creative assets can be stored immutably to prove authenticity and prevent accidental or malicious changes.
5. Legal hold data preservation – During litigation or investigations, immutable storage ensures relevant documents remain unaltered until the case concludes.
6. Long-term archiving – Scientific research, historical datasets, and digital media archives benefit from guaranteed preservation over decades without risk of silent corruption or unauthorized edits.
7. Secure configuration baselines – Critical system configuration files and baseline images can be locked to prevent unauthorized changes, ensuring consistency across environments.

Immutable Storage and Object Lock

S3 Object Lock is a feature of the AWS S3 API  that allows you to store objects using a Write Once Read Many (WORM) model. It enables you to protect your data from being deleted or overwritten for a specified period of time or indefinitely.

Key features of S3 Object Lock:

1. Immutability: When an object is locked using S3 Object Lock, it becomes immutable, meaning it cannot be deleted or overwritten by any user, including the root account. This ensures data integrity and protects against accidental or malicious modifications.
2. Retention Modes: S3 Object Lock offers two retention modes:
   • Governance Mode: In this mode, objects can be deleted or overwritten only by users with special permissions. It provides some flexibility for authorized users to manage data.
   • Compliance Mode: This mode provides the highest level of protection. Objects locked in compliance mode cannot be deleted or overwritten by any user, including the root account, until the retention period expires.
3. Retention Periods: You can specify a retention period for objects locked using S3 Object Lock. The retention period can be either a fixed period (e.g., 5 years) or an indefinite period. During the retention period, the object remains immutable.
4. Legal Hold: In addition to retention periods, S3 Object Lock also supports placing a legal hold on objects. When a legal hold is placed, the object becomes immutable until the legal hold is removed, regardless of the retention period.
5. Versioning: S3 Object Lock requires versioning to be enabled on the S3 bucket. When an object is locked, a new version of the object is created, and the lock is applied to that version. This allows you to protect specific versions of objects while still being able to create new versions.

Immutable Storage for Ransomware Protection

Ransomware is a type of malicious software. A common attack vector is to encrypt files until a sum of money (ransom) is paid to the attacker. Once ransomware infects a system, it encrypts the files and displays a message demanding payment, usually in cryptocurrency, in exchange for the decryption key. Some variants of ransomware not only encrypt files but also threaten to release sensitive data publicly if the ransom is not paid.

Immutable storage can be an effective defense against ransomware attacks by safeguarding the integrity and availability of critical data. Here’s how:

1. Prevents data encryption: Since immutable storage ensures that data cannot be modified or deleted once written, ransomware cannot encrypt the stored data. This means that even if the system is infected, the critical data remains accessible in its original, unaltered state.
2. Ensures data recovery: In the event of a ransomware attack, organizations can rely on immutable backups to restore their systems. These backups are protected from alteration, ensuring that the organization can quickly recover its data without paying the ransom.
3. Supports incident response: Immutable storage allows organizations to maintain a clean and unchangeable copy of their data. This helps in incident response by providing a reliable baseline for forensic analysis, identifying the extent of the compromise, and supporting recovery efforts.
4. Reduces operational downtime: By having an immutable copy of critical data, organizations can reduce the downtime associated with a ransomware attack. They can quickly restore operations by accessing unaltered data, minimizing the impact on business continuity.
5. Compliance and legal safeguards: For industries that must comply with strict data retention and integrity regulations, immutable storage ensures that data remains untampered even during a ransomware attack. This helps organizations avoid penalties and meet legal requirements while recovering from the attack.

Limitations of Immutable Storage 

Organizations should also be aware of the limitations of immutable storage:

• Cost: The inflexibility of not being able to modify or delete data can lead to increased storage costs, as new data must be continuously added without the option to remove outdated or irrelevant information until the retention period has expired. This requires careful capacity planning and management to prevent overhead costs from escalating.
• Not sufficient for data protection: While immutable storage guarantees data integrity, it does not inherently protect against all forms of data loss. For example, physical damage to storage devices or systemic failures could still result in data loss. Backup strategies and disaster recovery plans are still needed to complement the immutability feature.
• Complexity: Implementing and managing immutable storage systems require specialized knowledge and resources. Organizations must ensure that staff are adequately trained and that procedures align with the technologies used in immutable storage solutions to fully leverage their benefits and mitigate associated risks.

5 Best Practices for Immutable Backup Implementation

Organizations should consider the following best practices when implementing backups with immutable storage.

1. Align Backups with Business Objectives

Immutable backups are most effective when they directly support organizational goals. This requires engaging stakeholders across IT, compliance, and business units to ensure that the backup strategy aligns with regulatory requirements, operational needs, and long-term data retention policies. A solution that fails to integrate with the organization’s overall data management plan risks becoming costly and less effective in practice.

Scalability should be part of this planning process. As data volumes grow and new technologies are adopted, the backup environment must expand without major rework. A careful cost-benefit analysis is also critical; organizations need to weigh the upfront and ongoing expenses of immutable storage against the risks of data loss, regulatory fines, or business downtime.

2. Enforce Strong Access Controls

Even though immutability prevents data from being altered or deleted, attackers may still try to exploit weaknesses in access management. Strong authentication and authorization measures are essential to protect the environment. Role-based access control (RBAC) limits exposure by ensuring only users with specific responsibilities can view or manage backups, reducing the attack surface.

Implementing strict access controls also helps prevent insider threats. Not all employees need visibility into or interaction with backup data, so permissions should be tightly scoped. By restricting privileges to the minimum necessary, organizations reduce opportunities for mistakes or intentional misuse.

3. Protect Data with Encryption

Encryption strengthens immutable backups by ensuring that data remains confidential even if it is intercepted or accessed without authorization. Organizations should apply encryption both at rest in the storage system and in transit during data transfers. This dual-layer approach prevents attackers from exploiting weak points while data moves or resides in storage.

Secure management of encryption keys is just as important as encryption itself. Keys must be stored separately from backup systems and controlled through strict policies. If keys are compromised, encryption becomes ineffective, so organizations should enforce best practices such as key rotation and hardware-based key storage.

4. Secure the Backup Network

Backups are only as secure as the network that connects them. Immutable data can still be exposed if the surrounding infrastructure is vulnerable. Firewalls and intrusion detection systems should be deployed to monitor and block suspicious activity. Backup systems must also be segmented from production environments to reduce lateral movement if attackers gain entry.

Regular patching and updates are critical to maintaining network security. Outdated firmware, operating systems, or applications create gaps that attackers can exploit. By applying updates consistently, organizations close vulnerabilities before they can be leveraged, preserving the reliability of both backups and immutability guarantees.

5. Monitor and Audit Regularly

Immutable backups provide a strong defense, but oversight is still required to confirm they are functioning as intended. Advanced monitoring tools can detect anomalies, such as unusual access patterns or repeated failed login attempts, which may indicate malicious activity. Analytics can further highlight patterns that suggest vulnerabilities or attempted breaches.

Auditing provides an additional layer of assurance. Regular security and compliance audits ensure the environment meets both internal policies and regulatory standards. Reviewing access logs and system reports helps identify unauthorized activity, while scheduled hardware and software maintenance reduces the risk of failures.

Data Protection and Privacy with Cloudian HyperStore

Cloudian is a leading provider of object storage solutions that enable organizations to store, manage, and protect large amounts of unstructured data. With a focus on scalability, flexibility, and security, Cloudian’s HyperStore platform provides a foundation for enterprises and service providers to build their data storage infrastructure.

Cloudian has been at the forefront of supporting data immutability, recognizing its critical importance in ensuring data integrity and compliance. Through its integration with AWS S3 Object Lock API, Cloudian enables customers to create immutable data backups that are protected against accidental or malicious deletion, modification, or ransomware attacks.

This immutability feature, combined with Cloudian’s scalability and cost-effectiveness, makes it an ideal solution for organizations seeking to safeguard their data while leveraging the benefits of object storage.

Learn more about data protection with Cloudian.