https://blog.dshr.org/2020/08/optical-media-durability-update.html DSHR's Blog I'm David Rosenthal, and this is a place to discuss the work I'm doing in Digital Preservation. Thursday, August 20, 2020 Optical Media Durability: Update Two years ago I posted Optical Media Durability and discovered: Surprisingly, I'm getting good data from CD-Rs more than 14 years old, and from DVD-Rs nearly 12 years old. Your mileage may vary. A year ago I repeated the mind-numbing process of feeding 45 disks through the reader and verifying their checksums. It is time again for this annual chore, and once again this year I failed to find any errors. Below the fold, the details. +-----------------------------+ |Month|Media|Good|Bad|Vendor | |-----+-----+----+---+--------| |01/04|CD-R | 5| 0|GQ | |-----+-----+----+---+--------| |05/04|CD-R | 5| 0|Memorex | |-----+-----+----+---+--------| |02/06|CD-R | 5| 0|GQ | |-----+-----+----+---+--------| |11/06|DVD-R| 5| 0|GQ | |-----+-----+----+---+--------| |12/06|DVD-R| 1| 0|GQ | |-----+-----+----+---+--------| |01/07|DVD-R| 4| 0|GQ | |-----+-----+----+---+--------| |04/07|DVD-R| 3| 0|GQ | |-----+-----+----+---+--------| |05/07|DVD-R| 2| 0|GQ | |-----+-----+----+---+--------| |07/11|DVD-R| 4| 0|Verbatim| |-----+-----+----+---+--------| |08/11|DVD-R| 1| 0|Verbatim| |-----+-----+----+---+--------| |05/12|DVD+R| 2| 0|Verbatim| |-----+-----+----+---+--------| |06/12|DVD+R| 3| 0|Verbatim| |-----+-----+----+---+--------| |04/13|DVD+R| 2| 0|Optimum | |-----+-----+----+---+--------| |05/13|DVD+R| 3| 0|Optimum | +-----------------------------+ The fields in the table are as follows: * Month: The date marked on the media in Sharpie, and verified via the on-disk metadata. * Media: The type of media. * Good: The number of media with this type and date for which all MD5 checksums were correctly verified. * Bad: The number of media with this type and date for which any file failed MD5 verification. * Vendor: the vendor name on the media Surprisingly, with no special storage precautions, generic low-cost media, and consumer drives, I'm getting good data from CD-Rs more than 16 years old, and from DVD-Rs nearly 14 years old. Your mileage may vary. Tune in again next year for another episode. One observation is that the Mint Linux system I used to check the CDs (and a few of the DVDs) currently runs kernel version 5.0.0-32-generic. Each of the CDs read perfectly, but as each was mounted the kernel logged the following error: kernel: [ 182.504692] sr 2:0:0:0: [sr0] tag#0 CDB: Read(10) 28 00 00 05 64 30 00 00 02 00 00 00 kernel: [ 182.504699] print_req_error: critical target error, dev sr0, sector 1413312 flags 80700 kernel: [ 183.315607] sr 2:0:0:0: [sr0] tag#0 FAILED Result: hostbyte=DID_OK driverbyte=DRIVER_SENSE kernel: [ 183.315613] sr 2:0:0:0: [sr0] tag#0 Sense Key : Illegal Request [current] kernel: [ 183.315616] sr 2:0:0:0: [sr0] tag#0 Add. Sense: Invalid field in parameter list kernel: [ 183.315621] sr 2:0:0:0: [sr0] tag#0 CDB: Read(10) 28 00 00 05 64 30 00 00 02 00 00 00 kernel: [ 183.315624] print_req_error: critical target error, dev sr0, sector 1413312 flags 0 kernel: [ 183.315632] Buffer I/O error on dev sr0, logical block 176664, async page read Posted by David. at 8:00 AM # Labels: personal digital preservation, storage failures, storage media 5 comments: [blo] Dorothea said... Could you say a little bit more about the storage conditions? What's the temperature range on a "shirt-sleeve environment" and how's the humidity? A few years back my students rescued linguistics data, about ten years old, from fifty or so CDs kept in an academic office whose windows didn't open (common on our campus). About 10% had already gone bad. Anecdata, but I am curious about environmental tells. August 22, 2020 at 4:55 AM [icon_delet] [blo] David. said... The media are stored in their retail plastic 100-disk packages on a shelf in a closet in the laundry room of a non-air-conditioned house in Silicon Valley. Checksums were validated before storage, so they all started out known-good. They are all still good. August 22, 2020 at 7:11 AM [icon_delet] [bla] [Cim] Jason Scott said... Send them to me in your will, sir, and I'll continue the task in your honor. August 22, 2020 at 7:42 PM [icon_delet] [blo] David. said... Thanks, Jason, you have a deal. They are now labeled "Send to Jason Scott @ Internet Archive" August 22, 2020 at 8:15 PM [icon_delet] [blo] Angel G said... You managed to come across very good media then. I had issues with auto-erasing CD-R/DVD-R media only after the 4th year of storage. The manufacturer was Ritek. The DVDs have failed worse than CD. Since then I don't trust the optical media. The best CD I have was made by Ricoh. 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