El Miércoles, 15 de Agosto de 2007 05:45, Sebastian Bassi escribió: | On 8/14/07, Diego Saravia <[email protected]> wrote: | > aunque los guardes bien se descomponen, mas de 10 años no duran | | Los CDs (CD-R) mas viejos que tengo son del 96-97, y por suerte aun se | leen :) Pero lo que me pase a mi es anecdotico, por eso te paso este | documento, donde citan al instituto de estandares de USA que han hecho | pruebas en camaras donde simulan el paso del tiempo, para hacer luego | recomendaciones para las bibliotecas y oficinas del gobierno que | guardan datos en CDs: | http://www.clir.org/PUBS/reports/pub121/sec4.html | En resumen, depende mucho de la calidad del disco (no vas a comparar | esos sin nombre que te venden de a 1000 en "la casa del cd virgen" con | un Yamaha Gold que viene en caja individual) y de como lo guardes y | como lo trates: | | So what is the life expectancy of a disc? First, we must define life | expectancy. For most users, it means the length of time for which the | disc remains usable. But that implies some acceptable amount of | degradation. How much and what type of degradation is acceptable? | | With CDs and DVDs, the user does not notice early degradation because | the error detection and correction capability built into the system | corrects a certain number of errors. The user notices a problem only | when the error correction coding is unable to fully correct the | errors. | | One method for determining end of life for a disc is based on the | number of errors on a disc before the error correction occurs. The | chance of disc failure increases with the number of errors, but it is | impossible to define the number of errors in a disc that will | absolutely cause a performance problem (minor or catastrophic) because | it depends on the number of errors left, after error correction, and | their distribution within the data. When the number of errors (before | error correction) on a disc increases to a certain level, the chance | of disc failure, even if small, can be deemed unacceptable and thus | signal the disc's end of life. | | Manufacturers tend to use this premise to estimate media longevity. | They test discs by using accelerated aging methodologies with | controlled extreme temperature and humidity influences over a | relatively short period of time. However, it is not always clear how a | manufacturer interprets its measurements for determining a disc's end | of life. Among the manufacturers that have done testing, there is | consensus that, under recommended storage conditions, CD-R, DVD-R, and | DVD+R discs should have a life expectancy of 100 to 200 years or more; | CD-RW, DVD-RW, DVD+RW, and DVD-RAM discs should have a life expectancy | of 25 years or more. Little information is available for CD-ROM and | DVD-ROM discs (including audio and video), resulting in an increased | level of uncertainty for their life expectancy. Expectations vary from | 20 to 100 years for these discs. | | Few, if any, life expectancy reports for these discs have been | published by independent laboratories. An accelerated aging study at | NIST estimated the life expectancy of one type of DVD-R for authoring | disc to be 30 years if stored at 25°C (77°F) and 50% relative | humidity. This testing for R discs is in the preliminary stages, and | much more needs to be done. | | > por ejemplo las bacterias se los comen, peor si hay humedad | | Existe solo un hongo que puede comer una de las capas de un CD, y está | en Belice. Al menos ahi ese hongo naturalmente infecta los CDs. Quizas | haya bacterias que si las pones en cantidad suficiente sobre un CD te | lo estropean, pero no conozco que bajo condiciones normales de | almacenamiento haya bacterias que usen CDs como sustrato de | crecimiento. ja http://www.mastermagazine.info/articulo/12130.php -- `&' # Marcos Guglielmetti, co-director de # Musix GNU+Linux, 100% Software Libre para artistas _#_ http://www.musix.org.ar (#) / O \ + archivos: ftp://musix.ourproject.org/pub/musix ( === ) Ecología: http://autosus.wordpress.com `---' Personal: http://marcospcmusica.wordpress.com Bender: "En nombre de todo lo que es bueno y es lógico, damos las gracias por ésta energía química que vamos a absorber. Según el profeta jerimático: 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 1, 0, 0, 1, 1, 0, 1... ¡¡ 2 !! Amén." http://es.wikiquote.org/wiki/Futurama