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| Thread ID: 127147 | 2012-10-06 21:21:00 | Half life of data stored on a magnetic drive | ssssss (2100) | Press F1 |
| Post ID | Timestamp | Content | User | ||
| 1305529 | 2012-10-07 03:38:00 | . wikipedia . org/wiki/Hard_disk_drive_failure" target="_blank">en . wikipedia . org Since hard drives are mechanical devices, they will all eventually fail . While some may not fail prematurely, many hard drives simply fail because of worn out parts . Many hard-drive manufacturers include a Mean Time Between Failures figure on product packaging or in promotional literature . Recently, engineers at Google conducted their own real-world tests . (A PDF copy of the study is downloadable at: . google . com/archive/disk_failures . pdf" target="_blank">research . google . com) . The Google study identified several factors that contributed to the early death of a hard drive but the report drew no concrete conclusions . DriveSavers, a data recovery service provider that has been in business for over 20 years, recommends replacement of computer hard drives every 3-5 years . CD-ROM and DVD writeable media can fail over time due to degradation of the organic dye layer . Studies done by NIST under harsh conditions of light, temperature and humidity demonstrated sharp increases in bit errors after only 100 hours (with the exception of gold/phthalocyanine technology, which is far more durable) . Disks have been demonstrated to crack at 30,000 rpm due to centrifugal force . |
pctek (84) | ||
| 1305530 | 2012-10-07 03:47:00 | I know that but the term half life doesn't just refer to its size but also the type of decay which is radioactive decay. Hence me wondering why the term half life was used in the title. | Slankydudl (16687) | ||
| 1305531 | 2012-10-07 06:50:00 | I wouldn't worry too much about video data on a PRESSED disc like the BBC stuff. MPG playback algorithms are made to be tolerant of the odd unreliable byte here and there. At worse you'll get a momentary flash of blocky artifact during playback, but nothing that should bring playback to a halt unless there's quite gross levels of failure going on. But data (backups, zip files, documents etc) are NOT made to be tolerant of a bad byte, so place zero trust in burnt media for data, and low confidence in burnt media for video, and reasonable confidence in pressed media for data, and good confidence in pressed media for video. |
Paul.Cov (425) | ||
| 1305532 | 2012-10-07 08:47:00 | or you could use MPG to playback your media that you put on the disc. | Slankydudl (16687) | ||
| 1305533 | 2012-10-08 22:42:00 | Thanks. I have some blank Sony DVDs that have "archival reliabilty" written on them. Not true, it seems. Naughty Sony. |
ssssss (2100) | ||
| 1305534 | 2012-10-08 23:13:00 | Halflife can also apply to the decay of magnetic field strength over time which is appropriate. I Like Verbatim and Mitsubishi optical media (same disks actually verbatim are rebranded mitsi disks). They have consistently been in the top 3 of tests I've read and are much easier to get than Taiyo Yuden. But my experience with the long term reliabilty of any writeable optical disks has not been great, and DVDs seem to be worse than CDs in this respect. I have burnt CDs from the early days of CD writers that still read fine, but I have DVD's that have failed after a few months (especially princo). I have had a couple of the gold coloured disks and they do seem more reliable. Anything critical you should keep a backup of and periodically refresh it. I don't personally worry too much because there is nothing on my PC that can't be replaced. The worst thing would be losing my lossless rips of my CD collection which took me a few days to do so I have 2 copies of that on 2 differnet hard drives. But even then I still have the original CDs if it came to that. |
dugimodo (138) | ||
| 1305535 | 2012-10-08 23:40:00 | But even then I still have the original CDs if it came to that. Which will rot eventually. |
Agent_24 (57) | ||
| 1305536 | 2012-10-09 01:20:00 | Which will rot eventually. Well nothing lasts forever. Commercially produced CDs do last very well though, some of mine are 25+ yrs old and showing no signs of degradadtion. I expect the bulk of my CD collection to outlast me. I'm sure I recall when they first appeared the estimated life of an Audio CD if looked after was something like 70 yrs. I know some batches of CDs suffered from rot but I don't think it's all that common. Of more concern is either the discolouration of the plastic or the eventual oxidation of the alumininium. |
dugimodo (138) | ||
| 1305537 | 2012-10-09 01:54:00 | light and heat will also screw up the dye layer of the cd's | Slankydudl (16687) | ||
| 1305538 | 2012-10-09 01:55:00 | I know that but the term half life doesn't just refer to its size but also the type of decay which is radioactive decay. Hence me wondering why the term half life was used in the title. Half life doesn't specifically pertain to radioactive decay, it's just a term to indicate the time it takes for a quantity to halve in value, and is typically only used for values that exhibit exponential decay (in fact, it could only be used for such, in it's truest sense). In this context, one would assume it is referring to how long it would take for the magnetic strength of the disk in question to halve - which would probably be around 5 - 6 years. |
inphinity (7274) | ||
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