Long Term Data Preservation

Long Term Data Preservation (LTDP) can be seen from a technical and operational point of view highly influenced by a number of well defined aspects. Their analysis, their trade off wrt to actual technologies, concur :

  • to the SW architecture of the system
  • to the selection of the best HW (i.e. media) according to own specific needs.

ARK architecture and its possible deployments, has been based on such analysis. These aspects, mainly focused on the media used for data archiving,  are:

  • Total Cost of Ownership (TCO)
  • Longevity
  • Compatibility
  • Capacity and Performances
  • Need of Migration
  • Disaster Management

It is important to define what they are and how they affect LTDP system choices.

Total Cost Of Ownership (TCO)

Total cost of ownership (TCO) is a financial estimate intended to help buyers and owners determine the direct and indirect costs of a product or system.

Several attempts have been made to define an objective and recognized list of costs affecting the overall TCO. A Gartner study in 1987 consolidated it.

What is important to mention is that a cost of an archive is not only the HW but it is affected by a considerable number of other costs, in most of the cases becoming more and more important with time.

ARK supports several cost schemes (license schemes, cost per TB, …) and support its Customers in obtaining the lowest TCO selecting archiving media.



This aspect refers to the media used for archiving. The media longevity is declared by each vendor and it is bench-marked constantly by the IT market. On this latter case, in some cases, can be only extrapolated by some field tests (when media is new on the market). Several studies can be found on internet.

ARK uses the media that the Customer sets or, alternatively, suggests best media according to Customer functional and RAMS requirements.


Still on the media used for archiving, an important role can be played if the chosen media is also available in the consumer market. Some media, in fact, being available only for professional archiving solutions, have from one side a shorter lifetime of drives and from the other an higher costs. Again, ARK can manage almost all current media technologies and ACS proposes to its Customers the media which best fits their related requirements.

ARK supports several media and technologies, selected according to Customers archiving needs.

Capacity and Performances 

Media capacity plays a role to have a compact archive. If the media has a low capacity, the media change in the lobrary will result to be high and from the other the cost per byte archive can increase. Media performance is important when the load of the system is considerable, when the incoming and outgoing data flow is demanding. Without a performing media, the LTDP might not be able to sustain the data flows.

ARK supports several media and technologies, selected according to Customers archiving needs.

Need of Migration

Related to longevity, there is a need of data migration during archive lifetime. When the media is not longeve enough, when the drive can handle a considerably low number of read/write before it goes offline or in maintenance (MTBF), the LTDP system has to face extra operational and procurement costs.   A cost is also related to the risk to loose some data in the archive, becoming unreadable. This is considered one of the most important aspect to be analysed to implement an efficient LTDP system.

ARK can manage both magnetic and optical media. Latter ones have been proven to have low need of migration.

Disaster Management

For disasters management we intend all the practises to improve and sustain the business continuity of the archive and its data preservation in case of disasters, Some best practises in the IT market can be implemented, connected to different deployment and operational scenarios, such as:

  • use two archives on different media technology.
  • have two archive sites geographically separated (minimum distance suggested is 500 km).
  • use media copies, to be put offline in a different location.
ARK can implement all scenarios depending on the Customer RAMS requirements.