1. Digital Preservation: A Necessary Preservation Technique in Modern Era.
Animesh Bhattacharyya
Librarian,
Vivekananda Mahavidyalaya
Haripal,Hooghly.
Sourav Chatterjee
Ranaghat College
Ranaghat,Nadia

2. A Library holds and preserves the priceless heritage of mankind-such as facts, ideas, thoughts and different evidences of human development in different areas, ages and directions.

3. Digital preservation
“Digital preservation is the management of digital information over time. Preservation of digital information is widely considered to require more constant and ongoing attention than preservation of other media”.
(Wikipedia)

4. Purpose of digital Preservation
Digital documents are vulnerable to loss because of obsolescence of the media on which they stored, and they become in accessible and unreadable due to obsolescence of software and hardware.

5. Problems of digital preservation
The information in digital forms make it easy to create content and keep it up to date but at the same time brings many difficulties in the preservation of this content.

6. Challenges for preserving digital information
Changes in an organisation.
Content reorganisation.
Cessation of sponsorship.
Technological obsolescence.
Content format obsolescence.
Hacking and sabotage.
Disaster.

7. Technological obsolescence.
Digital data requires various layers of technological mediation before they can be understood by the user.
It can be divided in two ways
Hardware Problems
Software problems

8. Preservation strategies
Assessing the risks for loss of content posed by technology variables such as commonly used proprietary file formats and software applications.
Evaluating the digital content objects to determine what type and degree of format conversion or other preservation actions should be applied.
Determining the appropriate metadata needed for each object type and how it is associated with the objects.
Providing access to the content.

9. Additional strategies
Data creators and Publishers
Intellectual Property Right(IPR)
Collection Management
Staff expertise

10. Methods of preservation
1. Technology preservation
This proposes that digital data should be preserved on a stable medium with associated copies of the original application software, operating system ands relevant hardware devices. This approach actually suggests that the material as well as rthe technology need to be preserved. This is not a practical approach in for data preaservation as it is financially unfeasible to go for regular media refreshing.
2. Emulation
This relies on the preservation of the data in original format and proposes to build emulator programs that would mimic the obsolate hardware and software. In otherword this is the process of re-creation of hardware and software environment necessary to access a digital resource. This concept mainly emphasis on software related with data.
Contd..

11. Methods of preservation
3. Migration
Migration is a process that involves periodically moving files and digital objects from one hardware and software configaration to another, or from one generation technology to modern generationof computer technology as to preserve the digital information for future use. Migration also involves change in the configaration of the underlying data, not its intellectual content.This process requires continuous investment on upgradation of technology to maintain acess the old digital information.
4. Refreshing
Refreshing involves the periodic transfer of data from one physical storage medium to another to avoid the obsolescence of that medium.Sometimes new technology is unable to acess the older storage medium so, refreshing is necessary to achieve longivity.

12. Methods of preservation
5. Archeology.
Data archaeology is the process of recovery of data later on, using up-graded techniques available in future.This is essential for those digital information that has not been migrated but still vital in respective field.In this process data would be refreshed regularly but no migration would be performed and no software and hardware would be preserved to be emulated at a later storage.

13. conclusion
Preservation of document is nothing but the preservation of knowledge for future use. It is a challenging task for librarians. Digital preservation is a cost-intensive activity of continuing nature. continuous self development through workshops,trainings etc are needed to meet the challenges in digital environment

14. Thank you.