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What to do for long term storage of data? (on a DVD+R now)
Today at work, I backed up a PC hard drive that contains old scanned college
transcripts. The data on the hard drive does not exist anywhere else, and they have been running the machine for YEARS-no backup. Crazy, just ****ing crazy. So, I booted to a Ghost floppy and made an image of the hard drive (actually, 2 drives and 2 images). Then I burned them to DVD+R, I made 2 copies on DVD and kept the images on my PC. Gave a copy to the head lady in that dept. It occurred to me, that DVD+R isn't the best way to store data for the long term. I mean, they will never want to lose this data-EVER. What advice might you offer? Does anybody offer a service of making a real pressed DVD from a +R disc? That would be cool. THANKS! --Dan |
#2
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In article ,
dg wrote: Today at work, I backed up a PC hard drive that contains old scanned college transcripts. The data on the hard drive does not exist anywhere else, and they have been running the machine for YEARS-no backup. Crazy, just ****ing crazy. So, I booted to a Ghost floppy and made an image of the hard drive (actually, 2 drives and 2 images). Then I burned them to DVD+R, I made 2 copies on DVD and kept the images on my PC. Gave a copy to the head lady in that dept. It occurred to me, that DVD+R isn't the best way to store data for the long term. I mean, they will never want to lose this data-EVER. What advice might you offer? Does anybody offer a service of making a real pressed DVD from a +R disc? That would be cool. THANKS! --Dan Here's what the US National Institute of Standards has to say about DVD/CD media lifetime: http://www.itl.nist.gov/div895/carefordisc/ -- a d y k e s @ p a n i x . c o m Don't blame me. I voted for Gore. |
#3
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dg wrote:
Today at work, I backed up a PC hard drive that contains old scanned college transcripts. The data on the hard drive does not exist anywhere else, and they have been running the machine for YEARS-no backup. Crazy, just ****ing crazy. So, I booted to a Ghost floppy and made an image of the hard drive (actually, 2 drives and 2 images). Then I burned them to DVD+R, I made 2 copies on DVD and kept the images on my PC. Gave a copy to the head lady in that dept. It occurred to me, that DVD+R isn't the best way to store data for the long term. I mean, they will never want to lose this data-EVER. What advice might you offer? Does anybody offer a service of making a real pressed DVD from a +R disc? That would be cool. It can be done--there's probably some outfit near you that does it. The trouble is that the setup charge is far more than you want to pay. Magneto-optical is generally considered to be pretty good for long-term storage. So is DLT believe it or not. THANKS! --Dan -- --John Reply to jclarke at ae tee tee global dot net (was jclarke at eye bee em dot net) |
#4
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Previously J. Clarke wrote:
dg wrote: Today at work, I backed up a PC hard drive that contains old scanned college transcripts. The data on the hard drive does not exist anywhere else, and they have been running the machine for YEARS-no backup. Crazy, just ****ing crazy. So, I booted to a Ghost floppy and made an image of the hard drive (actually, 2 drives and 2 images). Then I burned them to DVD+R, I made 2 copies on DVD and kept the images on my PC. Gave a copy to the head lady in that dept. It occurred to me, that DVD+R isn't the best way to store data for the long term. I mean, they will never want to lose this data-EVER. What advice might you offer? Does anybody offer a service of making a real pressed DVD from a +R disc? That would be cool. It can be done--there's probably some outfit near you that does it. The trouble is that the setup charge is far more than you want to pay. Magneto-optical is generally considered to be pretty good for long-term storage. So is DLT believe it or not. For usual end user budget, get a 3.5" MOD (E.g. Fujitsu makes them). The media lifetimes are in the "we don't know" class with possibly 80 years. Every disk manufacturer garantees 30 years, most 50 years. And the drive manufacturers are commited to maintain backward compatibility with older media. Current genreation reads and writes (!) alll 5 media generations from todays 2.3GB media down to the first 128MB media. Also put a FAT filesystem on them, since that is likely readable for a long time, because it is so simple. And it is readable on almost any OS today. For image format the consent seems to be that TIFF is the way to go for long-term storage, because it is structured and well-documented. However GIF should also be fine. JPG is dangerous, they mess with the algorithms from time to time. Arno -- For email address: lastname AT tik DOT ee DOT ethz DOT ch GnuPG: ID:1E25338F FP:0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F "The more corrupt the state, the more numerous the laws" - Tacitus |
#5
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#6
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In article ,
wrote: On 15 Jan 2005 07:37:15 GMT, Arno Wagner wrote: Previously J. Clarke wrote: dg wrote: Today at work, I backed up a PC hard drive that contains old scanned college transcripts. The data on the hard drive does not exist anywhere else, and they have been running the machine for YEARS-no backup. Crazy, just ****ing crazy. So, I booted to a Ghost floppy and made an image of the hard drive (actually, 2 drives and 2 images). Then I burned them to DVD+R, I made 2 copies on DVD and kept the images on my PC. Gave a copy to the head lady in that dept. It occurred to me, that DVD+R isn't the best way to store data for the long term. I mean, they will never want to lose this data-EVER. What advice might you offer? Does anybody offer a service of making a real pressed DVD from a +R disc? That would be cool. It can be done--there's probably some outfit near you that does it. The trouble is that the setup charge is far more than you want to pay. Magneto-optical is generally considered to be pretty good for long-term storage. So is DLT believe it or not. For usual end user budget, get a 3.5" MOD (E.g. Fujitsu makes them). The media lifetimes are in the "we don't know" class with possibly 80 years. Every disk manufacturer garantees 30 years, most 50 years. And the drive manufacturers are commited to maintain backward compatibility with older media. Current genreation reads and writes (!) alll 5 media generations from todays 2.3GB media down to the first 128MB media. Also put a FAT filesystem on them, since that is likely readable for a long time, because it is so simple. And it is readable on almost any OS today. For image format the consent seems to be that TIFF is the way to go for long-term storage, because it is structured and well-documented. However GIF should also be fine. JPG is dangerous, they mess with the algorithms from time to time. Arno DVD-RAM is the now recommended system to use, and its used for Medical record backup.. 100,000 read writes and 100 year life.. Nothing else to touch it.. Got a citation for that ? I'm not pulling your chain, I need a citation for that figure if I'm going to recommend it to someone else. Here's what the National Inst of Standards has to say about CD/DVD media lifetime. http://www.itl.nist.gov/div895/carefordisc/ IMO, it's easy to fixate on any single aspect of long-term data retention. The media, the application, and the reader/drive, and the computer architecture+OS all have to survive in some reasonable form. For images and text, it's sort of easy since they are operating system independent. Busines data is a PITA, becasue the version of the application that reads the data needs to be recovered, along with the data. Either that or you just produce flat-file ASCII reports that are machine-indepedndent. IMO, common image formats will be understood, forever. So will documents encoded in HTML, and flat ASCII text files. Nobody's going to make a change to JPG that breaks the trillions of images that exist, already. As for the media and reader, you have to be prepared to copy your data to new media every few years, this solves the obsolete reader problem, and keeps you within the expected lifetime for any particular media technology. sh*t happens. you need to keep a couple generations of media, and a couple copies in each generation. Virtual machines and software emulators are becomming the salvation of people that archive computer applications needed to read old data that's in propriatery formats. There are companies that specialize in owning every old media reader ever made and they can recover your files for you, buy inm some cases you need to run an application to make sense of the data. -- a d y k e s @ p a n i x . c o m Don't blame me. I voted for Gore. |
#7
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#8
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Previously Al Dykes wrote:
In article , wrote: On 15 Jan 2005 07:37:15 GMT, Arno Wagner wrote: Previously J. Clarke wrote: dg wrote: [...] DVD-RAM is the now recommended system to use, and its used for Medical record backup.. 100,000 read writes and 100 year life.. Nothing else to touch it.. Got a citation for that ? I'm not pulling your chain, I need a citation for that figure if I'm going to recommend it to someone else. I got a non-citation on MOD (which is now 20 year old technology and well understood): An Engineer with Phillips told me they now estimate 80-100 year life after decades of accelerated ageing, but that the models are shaky for that long a time. They are confident to state publicly that the data on a MOD will keep at least 50 years. One more comment about DVD-RAM: MOD does mandatory verify of all data written and reallocated if the read-back is not perfect. DVD-RAM uses a disk technology similar to MOD, but has two problems which decrease reliability significantly in comparison: - For DVD-RAM with cartridge, the drive does not do automatic verifies. You can only hope your software driver does. However a software verify is significantly inferior to one done by the drive, since the drice can e.g. read at reduced amplifier settings on the verify and do other things to be more thorough than a normal read. - DVD-RAM without cartridge has mandatory verify by the drive, but you don't have the cartridge. That means less protection from physical damage and light. My personal opinion is that DVD-RAM is somewhere halfway between MOD and DVD-RW. Good, but not very good. Note that unlike the other DVD writable formats DVD-RAM uses phase-change and not dyes to store the data. It is similar to MOD in that regard. Arno -- For email address: lastname AT tik DOT ee DOT ethz DOT ch GnuPG: ID:1E25338F FP:0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F "The more corrupt the state, the more numerous the laws" - Tacitus |
#9
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Arno Wagner wrote:
Previously Al Dykes wrote: In article , wrote: On 15 Jan 2005 07:37:15 GMT, Arno Wagner wrote: Previously J. Clarke wrote: dg wrote: [...] DVD-RAM is the now recommended system to use, and its used for Medical record backup.. 100,000 read writes and 100 year life.. Nothing else to touch it.. Got a citation for that ? I'm not pulling your chain, I need a citation for that figure if I'm going to recommend it to someone else. I got a non-citation on MOD (which is now 20 year old technology and well understood): An Engineer with Phillips told me they now estimate 80-100 year life after decades of accelerated ageing, but that the models are shaky for that long a time. They are confident to state publicly that the data on a MOD will keep at least 50 years. One more comment about DVD-RAM: MOD does mandatory verify of all data written and reallocated if the read-back is not perfect. DVD-RAM uses a disk technology similar to MOD, Common misconception. DVD-RAM uses disk technology similar to DVD-RW. What's different is the formatting and encoding. but has two problems which decrease reliability significantly in comparison: - For DVD-RAM with cartridge, the drive does not do automatic verifies. You can only hope your software driver does. However a software verify is significantly inferior to one done by the drive, since the drice can e.g. read at reduced amplifier settings on the verify and do other things to be more thorough than a normal read. - DVD-RAM without cartridge has mandatory verify by the drive, but you don't have the cartridge. That means less protection from physical damage and light. My personal opinion is that DVD-RAM is somewhere halfway between MOD and DVD-RW. Good, but not very good. Note that unlike the other DVD writable formats DVD-RAM uses phase-change and not dyes to store the data. CD-RW, DVD+/-RW, and DVD-RAM all use basically the same phase change technology, changing a substance from an amorphous to a crystalline state and back--what varies is the detailed composition of the phase-change layer and the formatting and encoding of the disk. It's the write-once media that use dyes. It is similar to MOD in that regard. No. MOD does not use a phase change, it changes the orientation of a magnetic field in a material heated above the Curie point--the spots with the reversed field have a different polarization from the others, which is what allows reading. There is no phase change. There is a very good discussion of the chemistry of optical and magneto-optical recording at http://www.hkbu.edu.hk/~chem/Discworld Web version.ppt. Note that this is a PowerPoint presentation that can also be displayed using OpenOffice Impress. Arno -- --John Reply to jclarke at ae tee tee global dot net (was jclarke at eye bee em dot net) |
#10
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Previously J. Clarke wrote:
Arno Wagner wrote: Previously Al Dykes wrote: In article , wrote: On 15 Jan 2005 07:37:15 GMT, Arno Wagner wrote: Previously J. Clarke wrote: dg wrote: [...] DVD-RAM is the now recommended system to use, and its used for Medical record backup.. 100,000 read writes and 100 year life.. Nothing else to touch it.. Got a citation for that ? I'm not pulling your chain, I need a citation for that figure if I'm going to recommend it to someone else. I got a non-citation on MOD (which is now 20 year old technology and well understood): An Engineer with Phillips told me they now estimate 80-100 year life after decades of accelerated ageing, but that the models are shaky for that long a time. They are confident to state publicly that the data on a MOD will keep at least 50 years. One more comment about DVD-RAM: MOD does mandatory verify of all data written and reallocated if the read-back is not perfect. DVD-RAM uses a disk technology similar to MOD, Common misconception. DVD-RAM uses disk technology similar to DVD-RW. What's different is the formatting and encoding. Are you sure? Hmmm. Not good. but has two problems which decrease reliability significantly in comparison: - For DVD-RAM with cartridge, the drive does not do automatic verifies. You can only hope your software driver does. However a software verify is significantly inferior to one done by the drive, since the drice can e.g. read at reduced amplifier settings on the verify and do other things to be more thorough than a normal read. - DVD-RAM without cartridge has mandatory verify by the drive, but you don't have the cartridge. That means less protection from physical damage and light. My personal opinion is that DVD-RAM is somewhere halfway between MOD and DVD-RW. Good, but not very good. Note that unlike the other DVD writable formats DVD-RAM uses phase-change and not dyes to store the data. CD-RW, DVD+/-RW, and DVD-RAM all use basically the same phase change technology, changing a substance from an amorphous to a crystalline state and back--what varies is the detailed composition of the phase-change layer and the formatting and encoding of the disk. It's the write-once media that use dyes. It is similar to MOD in that regard. No. MOD does not use a phase change, it changes the orientation of a magnetic field in a material heated above the Curie point--the spots with the reversed field have a different polarization from the others, which is what allows reading. There is no phase change. There is a very good discussion of the chemistry of optical and magneto-optical recording at http://www.hkbu.edu.hk/~chem/Discworld Web version.ppt. Note that this is a PowerPoint presentation that can also be displayed using OpenOffice Impress. O.K., my opinion of DVD-RAM just dropped significanlty. I will stay with MOD. Thank's for the info and references! Arno -- For email address: lastname AT tik DOT ee DOT ethz DOT ch GnuPG: ID:1E25338F FP:0C30 5782 9D93 F785 E79C 0296 797F 6B50 1E25 338F "The more corrupt the state, the more numerous the laws" - Tacitus |
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