Archival Preservation 101: Cloud vs. Physical (Local) Storage

Bridget Lerette, Archivist, Harper College 

As with many issues in archives practice, the answer to the question of whether to use cloud or physical storage for digital preservation of archives and special collections is-- it depends. Cloud and physical storage each offers advantages and disadvantages, so the selection between the two will be dependent on the needs and resources of the institution.

Cloud storage is where data is hosted and maintained by an outside service provider. Data is accessed from the off-site data center via the Internet. All the hardware, software, and supporting infrastructure is handled by the service provider.

Physical (Local) storage is where data is stored on local physical drives, usually at the primary location of the institution as well as in backup locations. Data is accessed through the institution’s local network. The server(s) is/are controlled, administered, maintained, procured, etc. by the institution and its IT team.

The advantages of cloud storage include:

• Data is easily accessible via internet-connected devices;
• It generally requires lower initial set-up costs than local physical storage does since the institution only pays for the space used;
• Data is regularly backed up to multiple locations and has integrity checking without any intervention on part of institution;
• Storage in the cloud is scalable with minimal effort;
• Physical data loss is mitigated because of the multiple redundancies, firewalls, and encryption data centers employ to keep data safe; and
• Less in-house IT support and buy-in is needed.

The disadvantages of cloud storage include:

• Reliance on the internet can result in slow download speeds for data retrieval or the inability to access data at all in the case of a service disruption;
• Large amounts of data storage capacity may be cost prohibitive in comparison to physical (local) storage;
• Since cloud storage providers are hacked more often, security concerns for sensitive files that need to be protected and monitored with stringent controls arise;
• Potential loss of data with closure of accounts or expensive costs incurred when switching providers. The data needs to be accessible beyond the commercial lifespan of current technology or service providers and providers permanence is not guaranteed;
• Risk to data authenticity and integrity managed by third parties who have more locations and thus a greater risk of unauthorized physical access; and
• Copyright concerns and the need to manage permissions are intensified by the storage of data in the cloud.

The advantages of physical (local) storage include:

• Data recovery is available without the requirement of an internet connection;
• Full control of data and storage infrastructure because it is physically on-site;
• Local storage can be easily changed;
• Lack of third-party involvement with sensitive data and easy compliance with security measures that require data be stored on-site;
• Faster access to data because it does not rely on internet speeds;
• No hidden fees or paywalls; and
• Fewer copyright concerns.

The disadvantages of physical (local) storage include:

• Greater initial costs for setting up data storage devices, and upkeep is higher compared to cloud storage;
• Requires skilled services of IT and other local staff  for implementation and maintenance of data integrity;
• Risk of unwanted internal access and theft;
• Media durability and obsolescence are ongoing issues and there is a greater risk of external damage; and
• Expanding computing resources requires money, labor, expertise, procurement, hardware, software, monitoring systems and time.

If neither cloud nor physical (local) storage meet an institution’s needs and budget, the institution may also consider a hybrid solution for digital preservation. Hybrid storage allows for greater local control of sensitive assets while maintaining the flexibility of cloud storage. Combining online and offline storage techniques mitigates risk of data loss. A hybrid storage setup can provide quick onsite access to more frequently used data while less frequently accessed data is stored off-site. The data preserved would have greater redundancy to prevent loss.

Further information on digital preservation storage: 

• Digital Preservation Coalition’s Handbook
• The Council of State Archivists’ Resource Center 
• National Archives UK 

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