Digital Contents Digital Contents - PowerPoint PPT Presentation

Digital Contents Digital Contents สมชาย ประสิทธิ์จูตระกูล ประสิทธิ์จูตระกูล สมชาย

มาสราง + + เก็บแบบดิจิตอลกันเถอะ เก็บแบบดิจิตอลกันเถอะ มาสราง เอกสารดิจิตอล เอกสารดิจิตอล 101010000100101010 101000001010100011 – ไมเสื่อม ไมเสื่อม – 111100001010010000 000010100011100000 – ทําสําเนางาย ทําสําเนางาย – 100001111110100100 000101000101010010 – คนหาสะดวก คนหาสะดวก รวดเร็ว รวดเร็ว – 000010101000101001 Born-digital 001001010000010010 – จัดสงผานเครือขายได จัดสงผานเครือขายได – 000100100101001000 – ขนาดเล็ก ขนาดเล็ก ตนทุนต่ํา ตนทุนต่ํา 100001111110100100 – 000101000101010010 – ประหยัดกระดาษ ประหยัดกระดาษ – 000010101000101001 001001010000010010 – รักษาสิ่งแวดลอม รักษาสิ่งแวดลอม – 000100100101001000 000010101000101001 – ... ... – 001001010000010010

การสราง เก็บ เก็บ และใช และใช การสราง 100001001010 เขารหัส 100 . . . 110 010100011100 บันทึก เนื้อหา อาน ถอดรหัส 100001001010 100 . . . 110 010100011100

เลือกแบบไหนดี ? ? เลือกแบบไหนดี File formats File formats – txt (UTF txt (UTF- -8, Unicode, ASCII, ...) 8, Unicode, ASCII, ...) – – doc, doc, pdf pdf, xml, , xml, xdoc xdoc, jpeg, TIFF, wk1, ... , jpeg, TIFF, wk1, ... – Medias Medias – diskette, hard diskette, hard- -disk, tape, CD, DVD disk, tape, CD, DVD- -ROM, ... ROM, ... – Platforms Platforms – Intel Intel- -based, MS Windows, Mac based, MS Windows, Mac- -OS X, Solaris, OS X, Solaris, – Linux, Java, ... Linux, Java, ...

เลือกยาก เลือกยาก File formats File formats – ลาสมัย ลาสมัย ปกปด ปกปด (dbase, VisiCalc, WordPerfect, ...) (dbase, VisiCalc, WordPerfect, ...) – – เปลี่ยนรุนบอย เปลี่ยนรุนบอย (Word 6, 97, 2000, XP, 2003, ...) (Word 6, 97, 2000, XP, 2003, ...) – – ใชกับเฉพาะบาง ใชกับเฉพาะบาง platforms platforms ที่อาจไมมีแลว ที่อาจไมมีแลว – Medias Medias – เปลี่ยนรูปแบบบอย เปลี่ยนรูปแบบบอย (8, 5 (8, 5- -1/4 3 1/4 3- -1/2, ZIP, CD, ...) 1/2, ZIP, CD, ...) – – มีอายุใชงานไมนาน มีอายุใชงานไมนาน – – เสื่อมแลวไมรู เสื่อมแลวไมรู – Platforms Platforms – เปดแฟมเกา เปดแฟมเกา ตองใช ตองใช platform platform เกาซึ่งไมมี เกาซึ่งไมมี –

Magnetic Disks Magnetic Disks Common MTBF ranges are from 500,000 Common MTBF ranges are from 500,000 to 1,200,000 hours (57 to 137 years), to 1,200,000 hours (57 to 137 years), meaning half the drives in the population meaning half the drives in the population will fail before that time, half after. will fail before that time, half after. Seagate and Maxtor offer 5 year Seagate and Maxtor offer 5 year warranties on their SCSI HDs HDs warranties on their SCSI High probability of mechanical damage High probability of mechanical damage

Optical Disks Optical Disks CDs and DVDs are multilayered products, CDs and DVDs are multilayered products, consisting of polycarbonate outer coatings consisting of polycarbonate outer coatings (plastic), metal reflective layers, and dye (plastic), metal reflective layers, and dye layers layers Life- -spans range from 3 spans range from 3 - - (predicted) 300 (predicted) 300 Life years, depending on components years, depending on components Polycarbonate Layer CD-R or Metal Reflective Layer Dye Layer (Data Layer in Recordable CDs) CD-R/W Polycarbonate Layer

CD Metal Reflective Layers CD Metal Reflective Layers Metals Properties and Problems Metals Properties and Problems Least reflective, subject to Least reflective, subject to Aluminum Aluminum tarnishing. tarnishing. Most reflective, relatively safe from Most reflective, relatively safe from Silver Silver tarnishing. LE 100. tarnishing. LE 100. Slightly (5%) less reflective than Slightly (5%) less reflective than Gold silver, but very unlikely to decay. Gold silver, but very unlikely to decay. LE 300. LE 300.

Common CD Dyes Common CD Dyes Dye Color Properties and Problems Dye Color Properties and Problems Very photosensitive. Very photosensitive. Very deep Failure after 20 – –100 100 Very deep Failure after 20 Azo Azo blue hours of full spectrum blue hours of full spectrum light exposure. light exposure. Photosensitive. Failure Photosensitive. Failure Cyanine Blue after 100 – – 200 hours of 200 hours of Cyanine Blue after 100 full spectrum exposure. full spectrum exposure. Fairly stable. Failure Fairly stable. Failure Pthalocyan Very light Pthalocyan Very light after 500 – – 600 hours of 600 hours of after 500 ine green ine green exposure. exposure.

Digital Preservation Digital Preservation Preservation traditionally focused on the Preservation traditionally focused on the physical object. physical object. Preserving a digital object requires Preserving a digital object requires maintaining the ability to reproduce the maintaining the ability to reproduce the content from stored data. content from stored data. Over time, reproducing a digital object is Over time, reproducing a digital object is challenging because the format for challenging because the format for representing the content change along representing the content change along with hardware and software. with hardware and software.

สิ่งที่ตองเก็บรักษา สิ่งที่ตองเก็บรักษา 100001001010 เขารหัส 100 . . . 110 010100011100 บันทึก เนื้อหา อาน ถอดรหัส 100001001010 100 . . . 110 010100011100

Digital Preservation Digital Preservation Bit preservation Bit preservation – Transfer and refresh of data Transfer and refresh of data – Migration Migration – Transformation of data into new formats to Transformation of data into new formats to – allow for continued access allow for continued access Emulation Emulation – Recreation of original operating environment Recreation of original operating environment – for continued access for continued access Conservation Conservation – Maintaining original equipment for access Maintaining original equipment for access –

Digital Strategy for the LOC Digital Strategy for the LOC Recommendation: The Library should explicitly define the sets of digital resources for which it will assume long-term curatorial responsibility.

Building E- -Record Archive at NARA Record Archive at NARA Building E Be neutral with respect to migration, emulation, or other approaches. Save records in “preferred derived forms” in addition to the original bits. Save essential metadata. Archive as much information as possible about the software and work flow processes used to ingest the original records. Safeguard the bits Select the appropriate storage media.

LOCKSS LOCKSS Lot ot O Of f C Copies opies K Keep eep S Stuff tuff S Safe afe L Developed by Stanford Univ. Library Developed by Stanford Univ. Library Allows libraries to run web caches for Allows libraries to run web caches for specific journals specific journals Run on generic PC using open- -source source sw sw Run on generic PC using open Being tested at 40+ libraries worldwide Being tested at 40+ libraries worldwide with the support of 30+ publishers. with the support of 30+ publishers.