3.4   Choice of Digital Storage Media

Any storage medium is dependent upon specific combinations of hardware and software for access. The accessibility of information stored on such media is highly vulnerable in a rapidly evolving technological environment, even over relatively short timescales.

No digital storage medium can be considered “long term” or permanent and there will always be a need for periodical refreshing of storage media. Careful selection of media can maximise the periods between refreshment and simplify the refreshment process, in addition to ensuring that data is as secure as possible.

 

3.4.1   Criteria that maybe adopted before selecting the Type of Media to be used

The following criteria should be considered by data creators when selecting removable storage media.

 

3.4.1.1   Availability and Speed

Considering how often records need to be accessed and how quickly they need to be retrieved, will be based on business needs. Where records do not need to be accessed often or quickly, storage mode with a slower retrieval time (such as nearline or offline storage) may be acceptable. Where records do need to be accessed often or quickly, a storage mode with a faster retrieval time may be preferred, although this may incur a higher cost.

 

3.4.1.2  Longevity

The media selected for storage of digital public records should have a proven lifespan suitable for medium to long term retention. Longevity with a proven lifespan greater than 10 years is not necessarily an advantage as obsolescence of the hardware used to read the media is likely to be more significant than the deterioration of the media itself.

In the case of long-term digital public records, the selected method should be robust and have a clearly definable migration path and widespread industry support to improve the chances of forward compatibility.

3.4.1.3  Capacity

The media should have sufficient capacity appropriate to the collection of records being stored and appropriate to the physical size of the storage facilities. Minimising the number of volumes of media is generally more efficient and cost effective.

 

3.4.1.4  Viability

The media chosen and the hardware used to read it should support robust error detection for both reading and writing data, and for testing the integrity of the media after writing. Proven data recovery techniques should be available.

Media should be write-once or have a reliable write-protect mechanism to prevent accidental erasure and to maintain integrity of the records.

3.4.1.5 Obsolescence

The media and its supporting hardware and software should be based on open standards, mature, well established in the market, widely available, widely used and supported by multiple manufacturers. Leading-edge technology that is proprietary and restricted to a single manufacturer should be avoided. Proprietary storage methods and devices may be less widespread and less likely to be sustained and supported over time.

 

3.4.1.6 Cost

The costing of storage should consider the total cost of ownership, not just the cost of the actual media per gigabyte. The total cost of ownership includes the cost of hardware, software, any special storage environments and the resources required for active management, monitoring, integrity checking and support.

 

3.4.1.7  Susceptibility

The life expectancy of offline digital media varies depending on the format and quality of the media, storage conditions, handling and treatment. Damage resulting from deterioration will differ depending on the types of media and storage conditions. It may vary from corrupt sectors on a disk, resulting in one or more files becoming inaccessible, to the complete loss of all information on the media. Given the potential for digital public records to be lost as a result of media deterioration, it is critical that digital media integrity be monitored and periodic refreshing of media be scheduled.

 

The media and supporting hardware should have low susceptibility to physical damage and be tolerant of a wide range of environmental conditions without data loss. Magnetic media should have a high coercivity value (the intensity of magnetic field required to demagnetise a material) to minimise the chance of accidental loss or erasure by exposure to magnetic fields. Any measures required to counter known susceptibilities (such as packaging or storage requirements) should be affordable and achievable.

 

3.4.1.8   What you Need to Do

Actively manage your important digital content! Steps to consider:

  • Have at least two separate copies of your content on separate media—more copies are better.
  • Use different kinds of media (DVDs, CDs, portable hard drives, thumb drives or Internet storage); use reputable vendors and products.
  • Store media copies in different locations that are as physically far apart as practical.
  • Label media properly and keep in secure locations (such as with important papers).
  • Create new archival media copies at least every five years to avoid data loss.