Migration Is a Better Preservation

Migration Is a Better Preservation Approach Than Emulation Digital preservation has as its goal ensuring that a digital collection does not lose its usability no matter what the technological changes occur in the future. Preservation methods that are not appropriate result in the digital collection becoming inaccessible and within only a few years rendering it useless.

Digital data is under a continuous threat in that not only the data file type utilized but the media that the data is preserved on including hardware and software systems are all sources of vulnerability. Organizational management as well as the culture of an organization including financial limitations and priority on spending can result in digital collections being threatened. The largest threat according to one author is that of "technical obsolescence." (JISC Digital Media, 2013, p.1) Approaches to Preservation There are several approaches to preservation including: (1) migration; (2) refreshment; and (3) emulation.

(JISC Digital Media, 2013, p.1) Migration is a process of duplicating content from one specific format to a newer format. For example copying content from a CD-ROM to a solid-state flash drive. (JISC Digital Media, 2013, p.1, paraphrased) Refreshment is a process of copying data on the same type of format but one that is updated or newer. Finally, emulation is a process that is more complex and involves access of data on a system other than the system the data was designed to use.

This generally occurs when the original system is no longer available. Advantages & Disadvantages of Migration Migration has both advantages and disadvantages. One of the advantages of migration is that the strategy is broadly used and the procedures to conduct simple migration are established. Migration is a reliable method for "preserving the intellectual content of digital objects and is particularly suited to page-based documents." (Dressler, 2010, p.1) Migration is enabled through readily available conversion software.

(Dressler, 2010, paraphrased) the disadvantages of migration include that migration makes a requirement of the commitment of a great deal of resources both at the start of migration and across time.

Migration when done at the pint of obsolescence is reported as "labor intensive" although migration is such that can "be automated, because formats evolve so rapidly; as collections grow, the work involved in migration also increases." (Dressler, 2010, p.1) the migration on request is an approach that can be used for mitigation of the complexity because migration is not actually conducted in digital objects and standardization of formats enables batch migration to be more easily performed.

Another drawback of migration is that some of the data or attributes such as formatting may be lost during the process of migration and the record's authenticity may possibly be compromised. Loss of functionality is reported as a significant possibility in the process of migration especially with digital objects of a complex nature.

Migration makes the assumption that "content is more important that functionality or look and feel." (Dressler, 2010, p.1) Advantages and Disadvantages of Emulation Emulation is held as superior to migration in that current means are used to "mimic the environment of the original rendering of a digital object by emulating software applications, operating system, and hardware." (Dressler, 2010, p.1) Emulation is reported as a superior method for digital objects that are complex with examples stated being that of "websites or data sets." (Dressler, 2010, p.1) the original experience can be reflected more meaningfully through execution speed, display resolution, color, and any input devices like a keyboard or mouse can be moderated to reflect original experience in a more meaningful way." (Dressler, 2010, p.1) The difference between emulation and migration is that the process of emulation maintains the original software and hardware.

The advantages of emulation include that emulation enables the recreation of the "full functionality and exact look and feel of a digital object's performance" making emulation an approach that is attractive for use in the preservation of complex digital objects and objects where appearance and functionality are held to be significant properties.

(Dressler, 2010, paraphrased) Emulation is held in the work of Oltmans and Kol to be "more cost-effective for preserving large collections, despite the relatively high initial cots for developing an emulation device." (Dressler, 2010, p.1) Emulation is contrasted to migration in that migration is applicable to all the objects in a collection respectively, creating high ongoing costs" whereas emulation chaining for the future is likely to detract from this.

Emulation can be implemented "at a higher level than the migration approach" therefore, instead of the development of conversion solutions per format "institutions can develop emulation solutions per environment." (Dressler, 2010, p.1) Emulation has not been used widely in preserving over the long-term and there is a need for tests of practicality prior to conclusions being made about the reliability of emulation.

Additionally, as noted by Dressler (2010) the selection of emulation strategy ultimately requires "buying into a migration strategy because emulators themselves become obsolete" making the replacement of the old emulator with a new emulator a requirement or alternatively requiring that a new emulator be created. The work of Rothenberg reports that migration is: (1) labor intensive; (2) time-consuming; (3) expensive; (4) error-prone; (5) risky; and (6) non-scalable and as well that migration makes a requirement of new solution for every new format.

(in: Granger, 2000, p.1) Granger (2000) states of migration that it "has been the only serious candidate thus far for preservation of large scale archives" and that not all of these will be valid "with equal force all of the time, with migration many of these claims will vary on a case-by-case basis.

Moreover, one has to ask, 'Labor intensive, expensive, etc.,' compared with what?" (Granger, 2000, p.1) Granger states that the ideal approach would be one offering alternatives "for levels of safety and quality, volume of storage, ease of access, and other attributes at varying cots, and it should allow these alternatives to be changed for a given document, type of document, or corpus at any time in the future." ( ) in addition access to all documents should involve only one step rather than making a requirement of multiple layers of encapsulation to.