Current Preservation Strategies: needs and requirement

1.Introduction:

In recent decades, many major libraries and archives have established formal preservation programs for traditional materials which include regular allocation of resources for preservation, preventive measures to arrest deterioration of materials, remedial measures to restore the usability of selected materials, and the incorporation of preservation needs and requirements into overall program planning. Preservationists within the library and archival community have been instrumental in developing an array of tools and methodologies to reduce the decay of traditional materials and to restore books and documents that have deteriorated to such an extent that their longevity and usability are threatened. Provisions for fire protection and adequate environmental controls frequently are incorporated into new library and archival facilities. The success stories and regular use of established preservation methods are found almost exclusively in developed countries, and within developed countries in preservation of print materials in major institutions (Preservation of Archival Materials).Digital preservation raises challenges of a fundamentally different nature which are added to the problems of preserving traditional format materials. By digital preservation,  mean the planning, resource allocation, and application of preservation methods and technologies necessary to ensure that digital information of continuing value remains accessible and usable

2.Preservation Of  material:

 
Which strategies have the libraries, archives, museums and their financial backers developed to protect their digital resources? One of the two objectives of a digital resource preservation system is ensuring an intact and unadulterated digital data stream: i.e. preserving the data content, which makes up the digital objects. This objective can be successfully met if the objects stemming from heterogeneous sources and available on a wide range of storage media can be separated as early as possible from their original carriers and transferred to a homogenous storage system. Those responsible for archiving should preferably set up a functionally autonomous system of several parts, the main task of which is to preserve the digital resource materials. A major part of this system is automated checking mechanisms, which monitor the continual internal transfer of data within the system. The short half-life of technical platforms necessitates a constant change of data carrier generations and migration of data. Permanent preservation of material is not possible if the data material is inseparably linked to a particular data carrier and also to its fate. Technical measures designed to protect usage rights (e.g. copy protection techniques) typically lead to conflict situations in the medium term. In the meantime there is broad agreement that a digital archive can only take responsibility for digital resources, the data material of which they are capable of obtaining. Documentation of the "archiving status" is helpful in creating transparency here.

2.1. The challenges of digital preservation

The purpose of preservation is to ensure protection of information of enduring value for access by present and future generations. Libraries and archives have served as the central institutional focus for preservation, and both types of institutions include preservation as one of their core functions. In recent decades, many major libraries and archives have established formal preservation programs for traditional materials which include regular allocation of resources for preservation, preventive measures to arrest deterioration of materials, remedial measures to restore the usability of selected materials, and the incorporation of preservation needs and requirements into overall program planning.

Digital preservation raises challenges of a fundamentally different nature, which are added to the problems of preserving traditional format materials. By digital preservation, I mean the planning, resource allocation, and application of preservation methods and technologies necessary to ensure that digital information of continuing value remains accessible and usable. I intentionally use the term "continuing" rather than "permanent" value to avoid both the absolutism and the idealism that the term "permanent" implies.

2.2. Preserving usability

"Preservation of material", however, is only one of the prerequisites for ensuring the availability and usability of digital resources in the future. "Preserving the usability" of digital resources is a significantly more complex task than preserving the data material. If we take the scenario of a "depot system for digital objects" in which data streams are securely saved and are stored in ways, which are impervious to technical changes, we are still faced with a problem. Without further support, we are incapable of interpreting the archived data stream as the technologies necessary for accessing it (operating systems, user programs) are long since defunct. In order to solve this problem, a number of different strategies are being discussed and prototypes being implemented and tested. Conserving system environments in hard and software museums and keeping them available indefinitely is no longer regarded as a serious approach. The use of migration techniques, by contrast, has already been proven for preserving digital data material for simpler data structures or across a generation change of data carrier types. Complex digital objects elude the migration strategy, however, as the effort required for many individual cases is incalculable. For this reason, experiments are being carried out into techniques aimed at effectively emulating "historical" system environments. In Germany a number of different approaches are being pursued, amongst which formalized descriptions of object structures and presentation environments play a prominent role. All of these approaches apply late in the procedure once the digital object, with its variable quality digital preservation characteristics, has already been created. However, some key initiatives are aimed at promoting the use of long-term data formats and open standards right from the stage at which the digital objects are generated. Regardless of which of these strategies is applied, preservation of usability will not necessarily correspond to the original nature of the original object. It will be necessary to concentrate efforts on the core functions of digital resources, i.e. primarily on the factor 

2.3. Infrastructure of digital archives.

The ISO standard "Reference Model for an Open Archival Information System (OAIS)" - describes the infrastructure of a digital archive in the form of a model. The model succeeds in establishing a generally applicable view of the core functions of a digital archive which goes beyond the confines of individual user communities, archives, data centers, and libraries by delimiting and clearly labeling the function modules, interfaces and types of information objects. This represents a valuable basis for the relevant system operators to exploit synergies in commissioning, planning and implementing product systems. The OAIS describes a number of different function modules, which reflect the data flow, and the work processes of the archive: ingestion, metadata management, archival storage, preservation planning, administration and access. The "preservation planning" function module consists in turn of four part systems which are responsible for monitoring the environment conditions of the archive systems, identifying the effects of technical changes as early as possible and providing the basic planning for the long-term preservation of the objects stored in the system. The "monitor designated community" function ensures that current information on the users' needs is collated via interaction with the world outside the archive system. The information permits ongoing adaptation of the archive system's access procedure in line with the changing habits of the user world. This includes e.g. preferred data formats, access protocols and general communication via the system's external interface. The "monitor technology" function facilitates monitoring of the development of digital technologies in the world outside the system. The aim is to identify, at an early stage, developments which could have a harmful impact on the usability of the objects stored in the system. The "develop preservation strategies and standards" function receives the information from the first two modules and converts it into action recommendations to the system administration. Such recommendations can relate e.g. to the application of new standards when accepting publications to the archive. The system administration stipulations are implemented by the "develop packaging designs and migration plans" function. This includes implementing migration and emulation strategies. The information packages, which are exchanged at the interfaces of the individual modules of our archive system, receive instructions on their internal

3.Current Preservation Strategies and Their Limitations.

Most librarians and archivists have accepted the basic wisdom -- for now at least -- that digital preservation depends upon copying, not on the survival of the physical media. But copying, also referred to as "refreshing" or "migration" is more complex than simply transferring a stream of bits from old to new media or from one generation of systems to the next. Complex and expensive transformations of digital objects often are necessary to preserve digital materials so that they remain authentic representations of the original versions and useful sources for analysis and research.

Probably the most commonly used preservation strategy is to transfer digital information from less stable magnetic and optical media by printing page images on paper or microfilm. It seems ironic that just as libraries and archives are discovering digital conversion as a cost-effective preservation method for certain deteriorating materials, much information that begins its life in electronic form is printed on paper or microfilm for safe, secure long-term storage. Yet, high-quality acid neutral paper can last a century or longer while archival quality microfilm is projected to last 300 years or more. Paper and microfilm have the additional advantage of requiring no special hardware or software for retrieval or viewing. Perhaps this explains why in many digital conversion projects, the digital images serve as a complement to rather than a replacement for the original hard copy materials (Conway, 1994).

Another strategy for digital preservation is to preserve digital information in the simplest possible digital formats in order to minimize the requirements for sophisticated retrieval software. As new media and storage formats were introduced, the data were migrated without any significant change in their logical structure. This approach has the distinct advantage of being universal and easy to implement. It is a cost-effective strategy for preserving digital information in those cases where retaining the content is paramount, but display, indexing, and computational characteristics are not critical. As long as the preservation community lacks more robust and cost-effective migration strategies, printing to paper or film and preserving flat files will remain the methods of last resort for many institutions and for certain formats of digital information.

This approach has the advantage of preserving more of the display, dissemination, and computational characteristics of the original materials, while reducing the large variety of customized transformations that would otherwise be necessary to migrate material to future generations of technology. Although this strategy simplifies migration and may lower digital preservation costs by reducing the amount of customized reformatting needed as technology changes, it does not eliminate the need for regular migration of digital materials. Software and standards both continue to evolve and even repositories with structurally homogeneous holdings can expect to be required to migrate their digital materials periodically.

Migration strategies that involve reformatting of digital materials to a simple standard format usually eliminate the structure of documents and relationships imbedded in databases. Computation capabilities, graphic display, indexing, and other features often are lost, thus limiting future analytical potential. Normalization to standard formats is not always technically feasible and it usually is quite costly.

Archives and libraries must also contend with entirely new forms of electronically enabled discourse and new forms of artistic and cultural expression that do not have predecessors in the analog world. No current preservation method is adequate for preserving dynamic data objects from complex systems. There are no established conceptual models or technical processes for preserving multi-media works, interactive hyper-media, on-line dialogues, or many of the new electronic forms being created today. The archival requirements to preserve content, context, and structure and to maintain the capability to display, link, and manipulate digital objects only heighten their software dependency.

3.1Digital Preservation and Copyright.

If all information in the world was written on clay tablets or carved into marble, its preservation would be greatly simplified. Even paper, when manufactured and stored properly, can have a life measured in hundreds of years. Today, however, much of the information being produced is digital and digital formats are notoriously fragile. Either the media on which the information is stored becomes unreadable, or the hardware and software needed to read the work becomes obsolete. Think of that old 8" floppy disk in the back of the drawer with your attempt from twenty years ago to write the Great American Novel (in WordStar). The magnetic data might not still be readable; drives that can read the disk are scarce; and few word processing packages today can understand WordStar documents.

To preserve analog information resources, it is often sufficient to house them in a benign environment. In particularly bad cases, it might be necessary to make a microfilm or xerographic copy of the original, but copying is the exception rather than the rule. Digital preservation, however, starts with copying. At a minimum, files need to be copied from obsolete or decaying media, such as 8" floppy disks or 5 " floppies, to current storage media. Good preservation practice requires much more, including making multiple copies of files. Digital documents may need to be changed from WordStar to WordPerfect to Word format, or perhaps even converted to PDF or XML format. Every time you use a digital file, you must copy it. When digital documents are displayed in a computer, they are copied from the storage medium into the RAM memory of the computer where it is then displayed. Digital preservation and access is all about copying.

In copyright law, copying is known as "reproduction," and it's one of the exclusive rights of the copyright owner. The right to publicly display a work is also an exclusive right of the copyright owner, as is the right to make an adaptation, known as a "derivative work." Our desire to keep digital information around for the future runs smack into the exclusive rights of the copyright owner.

3.2.Storage Media.

The limited life of magnetic and optical media pose a significant problem, although this is not the primary limiting factor for digital preservation. Recent research on the longevity of magnetic media indicate a useful life span of 10 to 30 years if they are handled and stored properly. Some optical disk technologies promise life spans of up to 100 years. Most authorities argue that enhanced media longevity is of little value because current media outlast the software and devices needed to retrieve recorded information.

Nevertheless, improvements in the stability, capacity, and longevity of the base storage media are needed to drastically reduce the vulnerability of digital materials to loss and alteration and to lower storage costs. Ample research and experience provide evidence of what can go wrong with magnetic media as a result of binder degradation, magnetic particle instabilities, and substrate deformation (Van Bogart). Optical media are susceptible to damage from high humidity, rapid and extreme temperature fluctuations, and contamination from airborne particulate matter (U.S. National Archives and Records Administration). To prevent these problems, it is imperative to store magnetic and optical media under strict environmental controls that are not always available, affordable, or convenient. Even modest improvements which produce storage media with larger per unit storage capacities and greater tolerance to variations in temperature and humidity will lower preservation costs by lessening the need for strict environmental controls, reducing the frequency with which digital media must be "refreshed" through recopying, and decreasing the number of storage units that must be handled.

This raises the question, however, of whether research on incremental improvements in current storage technologies will benefit preservation in the long run or whether we should seek alternative approaches to digital storage that more adequately meet archival requirements. As a frame of reference it is worth remembering that microfilm, which is considered the only acceptable archival storage medium, lasts at least 300 years with minimal maintenance if stored properly. Last June, the Los Alamos National Laboratory announced the invention of a High-Density Read-Only Memory (HD-ROM) technology that uses an ion beam to inscribe information on pins of stainless steel, iridium, or other materials. The HD-ROM is capable of storing 180 times more information than current CD-ROM technology at roughly one-half percent of CD-ROM costs. According to the release about this technology, the HD-ROM is impervious to material degradation and it requires no bit stream interpreter because the technology can describe in human-readable form all of the instructions needed to interpret the data (LANL Ion Beam Storage). Such an approach illustrates the potential for solutions built on entirely new storage technologies.

4.Migration.

Better methods for migration of digital materials to new generations of hardware and software are much needed for digital preservation regardless of breakthroughs in mass storage technologies. Planning for migration is difficult because there is limited experience with the types of migrations needed to maintain access to complex digital objects over extended periods of time. When a custodian assumes responsibility for preserving a digital object it may be difficult to predict when migration will be necessary, how much reformatting will be needed, and how much migration will cost. There are no reliable or comprehensive data on costs associated with migrations, either for specific technologies and formats or for particular collections, and little research underway on methodologies that would reduce the costs and burdens of migration.

The preservation community as a whole would benefit tremendously from the development of backward compatibility paths that would be included as a standard feature of all software. Backward compatibility or migration paths would enable a new generation of software to "read" data from older systems without substantial reformatting and without loss of retrieval, display and computational capabilities. Although backward compatibility is increasingly common within software product lines, migration paths are not commonly provided between competing software products or for products that fail in the marketplace.

Stewards of digital material have a range of options for preserving digital information. One might preserve an exact replica of a digital record with complete display, retrieval, and computational functionality, or a representation of the record with only partial computation capabilities, or a surrogate for the record such as an abstract, summary, or aggregation. Detail or background noise might be dropped out intentionally through successive generations of migration, and custodians might change the format or storage media. Enhancements are technologically possible through clean-up, mark-up, and linkage, or by adding indexing and other features. These technological possibilities in turn impose serious new responsibilities to present digital materials to users in a way that allows them to determine the authenticity of the information and its relationship to the original record. Methods to document changes in digital objects during their life span need to be incorporated as an integral part of improved migration methods.

There are few well-developed methods for preserving and migrating software so that it might be used to recreate digital documents that have the "look and feel" of the original sources. Maintaining repositories of obsolete hardware and software has been discussed periodically, but usually dismissed out of hand as too expensive and not demonstrably feasible. This approach deserves more serious consideration as a strategy for maintaining continuing access to certain types of digital materials. Feasibility studies and cost/benefit analyses should be conducted to determine the technological, economic, and commercial feasibility of maintaining selected legacy software systems and performing specialized migrations or, alternatively, of building and maintaining software emulators. Such an approach would support replay of original sources and contribute to the preservation of software as a significant cultural and intellectual resource in its own right.

5. Management Tools.

A fourth area for research is in the development of management tools for digital libraries and archives that integrate descriptive control and maintenance with storage technologies. Dynamic digital objects, such as those found in hypertext systems, pose special management problems for both current and future retrieval and reuse. The boundaries of hypertext sources, like those found on the World Wide Web today, are difficult to ascertain because no single party or institution controls changes in the nodes and links that make hypertext objects live and highly responsive information resources. A high degree of volatility accompanies these objects because the contents of nodes change, the sites where information resources are stored change, and the links between nodes change, move, and vanish. Some recent tools, such as the MOMspider (Multi- Owner Maintenance Spider) and Web: Lookout are capable of traversing a portion of the Web and noting maintenance problems such as broken links, moved documents, modified documents, and objects that have exceeded their expiration dates (Ackerman and Fielding). While tools such as these are useful for current maintenance, they do not address long-term preservation concerns. If further developed to address preservation problems, tools such as these have the potential to serve as filters, identify similar or identical objects, and monitor for maintenance problems.

Research and development of tools that would imbed more intelligence about the preservation status of digital material into the objects themselves would make monitoring and maintenance of large digital collections more automatic. Current methods for monitoring the physical status of digital materials are labor intensive, unreliable, and potentially damaging to the materials themselves. Recommended procedures for monitoring physical deterioration of magnetic tape, for example, involve reading a small sample of tapes periodically to determine whether any data losses have occurred (Eaton). The potential exists to build monitoring and reporting mechanisms into digital objects, storage systems, and network architectures that could support self- reporting of physical status and initiate automatic maintenance procedures.

Despite differences, some lessons from traditional preservation are transferable to the digital environment. In order to avoid commitments that far exceed available resources and costly rescue and restoration efforts, preservation must become an integral part of the planning, design, and resource allocation for digital libraries and archives. Integration of preservation requirements and methods with access and maintenance systems is essential to fully and efficiently support the processes of migration, regeneration, and documentation of the life of digital objects. Planning for preservation must become an integral part of the design and management of digital libraries and archives. If left as an afterthought, there is little reason to believe that long-term preservation of digital information will be any more affordable than preservation of conventional formats has been.

6.Conclusion:

Digital preservation raises challenges of a fundamentally different nature, which are added to the problems of preserving traditional format materials. By digital preservation, I mean the planning, resource allocation, and application of preservation methods and technologies necessary to ensure that digital information of continuing value remains accessible and usable. I intentionally use the term "continuing" rather than "permanent" value to avoid both the absolutism and the idealism that the term "permanent" implies.

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