What storage media can compete with tape for long-term storage?

The death of tape is often announced. But are there any serious contenders for very long term storage?
The death of tape has been announced at regular intervals over the past few years.But the fact remains, it is still the easiest medium for many organisations to use, particularly if they want to physically carry backups off-site. It is relatively cheap, it is well-established as a storage medium, and individual tapes are portable and have a small footprint.

However, the major problem with tape is the length of time it takes to search and restore data required for a discovery request by a court or regulator, particularly as the timeframe for the retrieval of information can be as little as a few hours. Unfortunately, no storage medium is perfect for long-term retention, and organisations have to balance the pros and cons of each media type before deciding on the format for their retained data.

The main requirement for data that is retained under regulations or legislation is that the storage is WORM-compliant (Write Once Read Many), and disk, tape and optical can all comply with this requirement.

Disk-based storage is widely used by organisations that need to retain data. Most software- and hardware-based archiving solutions are based on disk, as it is easy and quick for end-users to search and discover unstructured information and also for organisations to execute e-discovery searches. Disk is also cheap, can be reused and is WORM-compliant, which is managed through software. However, the major problems with disk are its footprint and also the cost of power if the spindles are continually spinning, which make it less attractive for the very long-term retention of high volumes of data.

Optical media has a much smaller footprint than disk, and it is also relatively cheap. It has fast retrieval times, and is easily searchable. However, it has much smaller capacities than disk. Optical can usually only be used once as a WORM-compliant medium and it has to be physically destroyed to delete data. This means all data that is going to be destroyed at one time has to be stored on a single disk, otherwise the surviving data will have to be moved to another disk before the disk(s) containing data requiring disposal can be destroyed.

Despite the limitations of tape, it does have a future in the long-term retention of data. The older a piece of information or data, the less likely it is to be required. Therefore a good storage retention policy is to use disk-based storage for data or records that are likely to be requested. Once they are no longer needed, perhaps after they have not been used for a pre-determined period of time, they can be archived to tape. However, tapes must be properly indexed, labelled, and managed – perhaps using the physical records management capabilities of a document and records management solution – so that should a discovery request be received, they can be located speedily.

As technologies evolve, so will the discovery capabilities of tape, ensuring its future at least for a few more years.

About the expert: Susan Clarke joined Butler Group in 1997, where she writes the company's Technical Audits, covering topics ranging from ERP, application development tools, e-business products and CRM systems. She is Butler Group's specialist in the field of data management, which includes storage, databases and all aspects of Enterprise Content Management.

Read more on Data protection, backup and archiving