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Home , Data degradation, Digital Data Storage, Digital Linear Tape, Magnetic tape

DIGITAL MEDIA

Summary the preceding information on the medium. For On-going and rapid advances in technology require example, if you want to view a specific portion of you to store electronic records on media that a , you must first fast-forward through enable you to meet long-term operational and legal the preceding portion of the videotape. requirements. Your records must be trustworthy, ◆ Random. Some digital media allow users to access complete, accessible, legally admissible in court, the stored information from any physical place and durable for as long as you need them. Because on the media. For example, when you put a disk every digital storage option will eventually become into your personal ’s disk drive, you can obsolete, consider digital storage options that will access any single file stored on the disk without allow you to maintain records by migrating and/or having to first access all the files that precede it. converting them during their required retention period. Storage Measurement The storage capacity of digital media is measured in Digital Storage , the basic unit of measurement: Electronic records are digital data that are stored ◆ 1,024 bytes make a kilobyte (KB) on digital media. Digital data exist, at their most ◆ 1,024 KBs make a megabyte (MB) or 1,024,000 basic level, as just zeros and ones, or on and off. bytes For example, black and white photographs in the ◆ 1,024 MBs make a gigabyte (GB) or newspaper are printed as a series of either black 1,024,000,000 bytes or white dots (0 or 1, on or off). The complex organization of a large number of dots allows the ◆ 1,024 GBs make a terabyte or 1,024,000, 000,000 human eye to complete the image. The digital data bytes in an electronic record use the same principle to For example, a one-page, text-only letter might be organize digital data into the record to make the 20 KB, a graphics file might be 200 KB, and a record readable. A (short for binary digit) is the fifty-page, desktop-published document with smallest unit of data in a computer. A bit has a graphics might be 2 MB. single binary value, either 0 or 1. Digital data are stored on digital media. Digital Storage Options media are divided into three main types: As part of a records management plan for electronic ◆ Magnetic. On magnetic media, the digital data are records, you will need to determine where and how encoded as microscopic magnetized needles on these records will be stored. This decision will be the surface of the medium (e.g., disk or tape). based on the likelihood of access to those resources versus the overall cost in maintaining them. Your ◆ Optical. On optical media, the digital data are options for storage include the following: encoded by creating microscopic holes in the surface of the medium (e.g., disk). Online. Properly designed storage in your computer ◆ Solid State. Containing no moving parts, solid- system may provide full access to appropriate users. state media encode digital data by applying Online access means that the record is accessible small voltages that temporarily induce a group immediately through your network (e.g., on your of transistors either on or off (e.g., network server or on your personal computer’s media, USB removable memory). hard drive). This option maintains the greatest functionality but requires more expensive network storage. Sequential Versus Random Access MORE ➔ Access to digital information on digital media is South Carolina Department of Archives & History divided into two types: Electronic Records Management Guidelines ◆ Sequential. Sequential access requires the user Digital Media March 2008, Version 2 to access specific information by accessing Page 1 Nearline. Nearline storage includes storage in a — Linear Tape-Open (LTO). Linear Tape Open system that is not a direct part of your network, but is an open standard system. that can be accessed through your network (e.g., Similar to DLT in capacity and speed, LTO’s an optical media jukebox). This option maintains standardized format allows interoperability a moderate amount of functionality. While the between tapes and tape drives made by storage space is cheaper than online storage, different manufacturers. nearline storage requires that the user take time to — Videotape. Videotape provides sequential manipulate both the files and media of choice to access to footage (e.g., feature films). access the records. Of the options available for , Offline. Offline storage refers to storage that is not overall life expectancy is greater with DLT and accessible through your network (e.g., removable LTO tape. With proper care and handling, the life media such as magnetic tape). This option trades expectancy of DLT and LTO should be greater than functionality for stability, but maintains records in ten years. Currently magnetic tape is the preferred an electronic format. method for security , especially when needed for long-term retention. Magnetic Media Magnetic media include: Optical Media ◆ Magnetic disk. Magnetic disks include the hard Optical media options include: disk found inside your computer that stores the ◆ Compact Disk (CD). Compact disks come in a programs and files you work with daily. Magnetic variety of formats. These formats include CD-ROMs disks provide random access. Also included are: that are read-only, CD-Rs that you can write to — Removable disk. Removable disks include the once and are then read-only, and CD-RWs that relatively small-capacity floppy disks, as well you can write to in multiple sessions. CD-RW disks as the larger-capacity peripheral disks, such as have less life expectancy than non-rewritable the Iomega Zip disks. ones. CD is relatively stable and with proper error — External Hard Drive. External hard drives are checking suitable for of five years encased in a plastic housing and connected before refreshing. via cable to a computer port. In this way, a ◆ Write-Once, Read-Many (WORM) disk. WORM disks single processor can have access to the data require a specific WORM disk drive to enable on multiple hard drives. the user to write or read the disk. WORM disks function the same as CD-R disks. ◆ Magnetic tape. Magnetic tapes come in reel- to-reel as well as cartridge format (encased ◆ Erasable optical (EO) disk. The user can write to, in a housing for ease of use). The two main read from, and erase from EO disks as often as advantages of magnetic tapes are their relatively they can magnetic disks. EO disks require special low cost and their large storage capacities (up hardware. to several gigabytes). Magnetic tapes provide ◆ Digital versatile disk (DVD). These disks are also sequential access to stored information which called digital video disks, but do not necessarily is slower than the random access of magnetic include video. DVD disks are types of optical disks. Magnetic tapes are a common choice for disks with more storage capacity than CD-ROMs. both long-term storage and the of large Various types of DVD are often incompatible. volumes of information. Because of the rapid improvements in DVD technology and incompatibility issues, DVD is — Tape (DAT). DATs are in a not an ideal storage medium for your records. cartridge format a little larger than a credit Common types of include: card. The industry standard for DAT cartridge format is a (DDS) cartridge. — DVD-ROM. These DVDs are read-only disks that DDS cartridges provide sequential access. DAT also have enough storage capacity for a full- is prone to significant data degradation over length feature film. They are accessed using time. a special DVD drive attached to a personal — (DLT). DLT is a high speed magnetic tape and drive system in cartridge MORE ➔ format that can hold up to 70 Gigabytes of South Carolina Department of Archives & History Electronic Records Management Guidelines data. Super DLT can hold up to 100 GB on a Digital Media single cartridge. DLT offers significant speed March 2008, Version 2 and storage advantages over DAT. Page 2 computer. Most of these drives are backward- migrate all data stored on them to a stable medium compatible with CD-ROMs and can play DVD such as magnetic tape. video disks. — DVD-RAM. DVD-RAM are rewritable disks with Digital Media Capacity exceptional storage capacity. They come in Table 1 summarizes the capacity of the basic digital one- or two-sided formats. Rewritable disks media options. You should research the specific have less life expectancy than non-rewritable medium and manufacturer for exact specifications, ones. including cost. Because of rapid technology — DVD+RW and DVD-RW. These are a direct developments in a highly competitive market, the competitor to DVD-RAM that offer similar costs for each option change frequently. functionality, are rewritable and have slightly Table 1: Storage Capacity of Digital Media Options greater storage capacity. — DVD-R and DVD+R. DVD-Rs and DVD+Rs can be Storage Media Capacity (Uncompressed) written to once and are then read-only. Magnetic Media — DVD+R DL also called DVD+R9 (DL stands for External hard disk Up to 1 TB Dual Layer). Employs two recordable dye layers, Removable disk 1.44-120 MB each capable of storing nearly the 4.7 GB capacity of a single-layer disc, almost doubling Magnetic tape 20-180 MB the total disc capacity to 8.55 GB. DAT 24+ GB — DVD+RW DL is a rewritable with DLT 70+ GB storage cpacity of 8.5 GB. DVD+RW DL discs employ two rewritable dye layers. LTO 200 GB — Blue-ray DVD and HD-DVD. Competing DVD Videotape Up to 8 hours of video technology offering higher storage capacity Optical Media than previous DVD formats. CD 650-800 MB WORM (CD-R) 650-800 MB Because DVD technologies are undergoing EO 650-800 MB rapid development, DVDs created using DVD 4.7-27 GB one type of equipment might not be viewable on all systems. DVD is an HD DVD and attractive format due to its high storage Blue-ray Disc 15-50 GB capacity. However, due to the lack of a Solid State Media single standard for this technology it Flash memory 256 MB-155 GB is advisable to consider other options, especially for vital records and records Note: Numbers current as of February 2008 requiring long term storage. Media Life Expectancy Solid State Media All storage media have finite life spans dependent Solid state media include various removable devices on a number of factors, including manufacturing utilizing flash memory. Small cards and “memory quality, age and condition before recording, sticks” offer storage capacities between 32 MB and handling and maintenance, frequency of access, 155 GB. Handheld known as Personal and storage conditions. Depending on storage Data Assistants (PDAs) rely on solid state memory conditions and the quality of manufacturing, the to store information such as calendars, word life expectancy of magnetic media ranges from 10 processed documents and spreadsheets. Due to its to 20 years, while optical media may last 30 years relative newness, the long-term storage capability or longer. However, in real life situations, most of solid state technology is questionable. This type media life expectancies are significantly less. For of media should only be used for working copies. If more information on the storage of digital media vital records are created or saved on flash memory MORE ➔ devices they should be transferred to another media South Carolina Department of Archives & History as soon as possible. Therefore, avoid storing any Electronic Records Management Guidelines Digital Media records on this media for an extended length of March 2008, Version 2 time. Users of solid state devices are encouraged to Page 3 to preserve longevity, refer to the Digital Media ◆ Speed of access. When selecting a digital storage Storage: Facilities and Procedures guideline. medium, consider how quickly you or authorized Unlike and microfilm, no single digital members of the public may need to access your medium and very few digital file formats will suffice records. You may find that some types of records for long term or permanent storage (10+ years) require fast access, while others do not. For at this time. Therefore, records stored digitally example, you may need fast access to key policy will require ongoing attention and maintenance decisions, but not to employee records. including periodic sampling of recorded media at 1 ◆ Capacity. The volume of records that you can year intervals, “refreshing” or re-recording of digital store on the medium will be a key consideration. records onto new media, and format migration/ Examine the volume of the records you now store, conversion to ensure successful preservation. and try to determine what your needs may be Before they are ten years old, copy tapes onto in the future. Consider the official definition of new tapes that have been tested and verified for a record and whether that definition will affect accuracy. CDs should be re-copied every five years the records volume that you need to manage. For or as indicated by sampling. For more information example, you may anticipate greater use of e-mail on migration and conversion see the File Formats and the expansion of your web site, which would guideline. affect future capacity. ◆ Longevity. Research how long the industry will In addition to media life expectancy, hardware support various media options and compare those must be available that allows you to easily read figures with the time period prescribed by the and retrieve your stored data. When selecting new approved records retention schedule. You may storage systems, it is a good idea to stay with find a medium that meets all your needs, but is well-known, supported and proven technologies. not widely used or has a high risk of becoming Although new technology may offer certain unique obsolete, thereby limiting its usefulness. benefits, it may also quickly become obsolete if the ◆ technology fails to catch on with consumers. Durability. Research how easily a given medium can be damaged or will deteriorate. You may find that a medium that deteriorates after three years will still be a suitable option for records that Remember that all records management need to be retained for only one year. Be sure to strategies should include the use review your records retention periods. of records retention schedules. A ◆ Versatility. If your records contain multiple records retention schedule lists the file formats (as described in the File Formats types of records by series, provides a guideline), research how many file formats a brief description of each series, and medium can store. For example, a determines how long they should be cannot store large graphics files, but a CD or a kept, including their final disposition. DVD can store graphics, text, audio files, or video Because record schedules are designed to files. manage records and not storage media, ◆ Cost. Assess the costs and benefits of each series that include multiple formats medium you consider. Be sure to discuss the costs (paper, electronic, audio, etc.) should of converting and/or migrating records, as well as be managed under a single schedule the basic costs of the system. whenever possible. ◆ Compatibility. Assess the backward and forward compatibility of the digital media you are Suggestions for Better Digital Media considering. For example, DVD-ROM drives are backward-compatible for CD-ROMs, but a CD- Decisions ROM drive is not forward-compatible for DVD- ◆ Planning. In addition to choosing a storage ROMs. This discussion will help you to determine medium, you should establish procedures to how often you may need to upgrade supporting refresh your digitally stored records periodically. computer systems, migrate records, and/or Due to built-in error correction circuits, data convert records. degradation can go unnoticed at first, and MORE ➔ periodic testing may not discover failing media South Carolina Department of Archives & History until it is too late. Refreshing digital media Electronic Records Management Guidelines occurs when you copy stored data from old to Digital Media March 2008, Version 2 new digital media. Page 4 ◆ Portability. Some media, such as DVD-ROMs, are [U.S. Public Law 106-229] encourages the use of very portable, while hard disks in a computer electronic documents and signatures, although it processor are not. Consider whether you will need goes further to provide some guidelines regarding special devices to read the records. For example, standards and formats. For more information not all organizations are equipped with DVD- on UETA see Appendices A6 and A7 of the ROM players. Consider who will be accessing your Trustworthy Information Systems Handbook. records. For example, will the public, the press, or ◆ Health Insurance Portability & Accountability other agencies frequently access your records? Act of 1996 [HIPAA] (Public Law 104-191), which establishes security and privacy standards Legal Framework for health information. The Act protects the For more information on the legal framework you confidentiality and integrity of “individually must consider when selecting digital storage media, identifiable health information,” past, refer to the Records Management in an Electronic present or future. Visit the HIPAA website at Environment guideline in the Electronic Records www.hhs.gov/ocr/hipaa/ for additional Management Guidelines and Appendix A6 of the information. Trustworthy Information Systems Handbook guideline. Also review the requirements of the: Annotated List of Resources ◆ South Carolina Public Records Act [PRA] (Code Primary Resources of Laws of South Carolina, 1976, Section 30-1- Beyers, Fred R. Information Technology: Care and 10 through 30-1-140, as amended) available at Handling for the Preservation of CDs and DVDs — A www.scstatehouse.net/code/t30c001.htm, which Guide for Librarians and Archivists. NIST Special supports government accountability by mandating Publication 500-252. Gaithersburg, MD: National the use of retention schedules to manage records Institute of Standards and Technology; Washington, of South Carolina public entities. This law D.C.: Council on Library and Information Resources. governs the management of all records created by October 2003. agencies or entities supported in whole or in part www.itl.nist.gov by public funds in South Carolina. Section This guide discusses the physical characteristics 30-1-70 establishes your responsibility to of various optical media, as well as methods for protect the records you create and to make their proper care and handling to ensure longest them available for easy use. The act does not possible use in any given environment. A useful discriminate between media types. Therefore, glossary is included. records created or formatted electronically are Dollar, C. . Authentic Electronic Records: Strategies covered under the act. for Long-Term Access. Chicago: Cohasset Associates, ◆ South Carolina Uniform Electronic Transactions Inc., 2000. Act [UETA] (Code of Laws of South Carolina, 1976, This book provides a comprehensive overview of Section 26-6-10 through 26-6-210). Enacted electronic records management, with chapters on in 2004, UETA facilitates electronic commerce key concepts, long-term access, best practices, and and electronic government services by legally developing an action plan. The book also includes placing electronic records and signatures on a comprehensive bibliography, as well as useful equal footing with their paper counterparts. appendixes covering such topics as technology UETA officially repeals the 1998 South Carolina for records management, electronic records Electronic Commerce Act (Code of Laws of South preservation costs, conversion standards, media life Carolina, 1976, Section 26-5-310 through 26-5- expectancies, and a preservation metadata model. 370). The purpose of UETA is to establish policy relating to the use of electronic communications The PC Technology Guide and records in contractual transactions. This law www.pctechguide.com does not require the use of electronic records This site is a comprehensive resource on all aspects and signatures but allows for them where agreed of the personal computer. Topics include hardware, upon by all involved parties. While technology software, computer use, and digital media. neutral, the law stipulates that all such records ➔ and signatures must remain trustworthy and MORE accessible for later reference as required by South Carolina Department of Archives & History Electronic Records Management Guidelines law. Similarly, the federal Electronic Signatures Digital Media March 2008, Version 2 in Global and National Commerce (E-Sign) Act Page 5 Saffady, W. Managing Electronic Records. 2nd ed. Puglia, S. “Creating Permanent and Durable Prairie Village, Kan.: ARMA International, 1998. Information: Physical Media and Storage Standards.” This book provides a thorough discussion of the CRM: Cultural Resource Management 22 (1999): basic principles of electronic records management. 25-27. Chapters include concepts and issues, electronic http://crm.cr.nps.gov/archive/22-2/22-02-10.pdf storage media and formats, file formats, the Refer to this web page for a list of references inventory of electronic records, retention schedules, on creating and storing records, including paper managing vital electronic records, and managing records, microfilm, and electronic records. files and media. The book also includes a South Carolina Department of Archives and History, comprehensive glossary and bibliography. State Archives Department. Trustworthy Information Webopedia Systems Handbook. Version 2, March 2007. http://webopedia.internet.com http://arm.scdah.sc.gov/erp/tishandbook.html This comprehensive online encyclopedia for the This handbook provides an overview for all information technology community provides an stakeholders involved in government electronic easy-to-understand, searchable database of terms. records management. Topics center around ensuring accountability to elected officials and Whatis?Techtarget citizens by developing systems that create reliable http://whatis.techtarget.com and authentic information and records. The A comprehensive online encyclopedia for the handbook outlines the characteristics that define information technology community. trustworthy information, offers a methodology for ensuring trustworthiness, and provides a series of Additional Resources worksheets and tools for evaluating and refining International Council on Archives. Guide for system design and documentation. Managing Electronic Records from an Archival Perspective. France: International Council on U.S. General Services Administration. “Applying Archives, 1997. Technology to Record Systems: A Media Guideline.” www.ica.org Information Resources Management Services, This handbook provides a comprehensive overview KML-93-1-R. (Washington, D.C., 1993). of electronic records management from an Published in 1993, this booklet from the federal archival perspective. The handbook provides useful government provides an overview of digital information on key concepts, such as life-cycle storage media considerations. Topics include management, legal issues, technological issues, an introduction to concepts and definitions of and implementation. storage options, physical properties of different media (e.g., paper, microfilm, digital storage, COOL (Conservation OnLine): Electronic Storage Media magnetic media, optical media), organization http://palimpsest.stanford.edu/bytopic/electronic- records, capturing and converting records, and cost records/electronic-storage-media considerations. These pages are part of the Conservation OnLine, Resources for Conservation Professionals web Van Bogart, Dr. John W.C. Magnetic Tape Storage site at Stanford University. This web page is a and Handling — A Guide for Librarians and collection of materials from other sources about Archivists. National Media Laboratory. St. Paul, electronic conservation, including resources on MN. The Commission on Preservation and Access; disaster recovery, electronic media, electronic Washington, D.C. June 1995. formats, and storage environments. http://www.clir.org/pubs/reports/pub54/ This guide discusses the physical characteristics Cornell University. “ Management: of magnetic media, as well as methods for their Selecting Short Term Strategies For Long Term proper care and handling to ensure longest possible Problems” use in any given environment. A useful glossary is www.library.cornell.edu/iris/tutorial/dpm/index.html included. An online tutorial available from Cornell University Library. The tutorial provides basic information including terms and concepts related to digital preservation. Includes images and descriptions of South Carolina Department of Archives & History obsolete media and media that is in danger of Electronic Records Management Guidelines Digital Media becoming obsolete in a section entitled “Chamber March 2008, Version 2 of Horrors.” Page 6