On Thu, 1 Aug 2019 23:09:32 -0400 (EDT) "D. Hugh Redelmeier via talk" <talk@gtalug.org> wrote:
- petroglyphs: long long time
- clay tablets: millennia
- paper (pre-wood-pulp): five hundred years
- paper made from wood pulp: 75 years
- punch cards and paper tape: 100 years
- 9-track mag tape: 10 years
- digital cassette tape 4 years (formats changed too quickly)
- floppy disks: 5 years? Depends on the format (consider 3.0" floppies)
- USB flash drives: I've had them die after a year, but that's not expected.
- hard drives: death by standards evolution. Try finding an ST506 controller. Or MFM, ESDI, SCSI, FireWire. Support for even PATA is fading.
- Laser Disc, Magneto-optical disks, CD-ROM, DVD (multiple standards), BluRay: each has standards that get obsolete. The actual data may deteriorate too. I do have some DVD that claim to have a lifetime of over 100 years.
Hugh, I copy my HDD backup to Blu-Rays periodically. Occasionally, I have had to recover stuff from them, and it has always worked. Typically, this was months after the fact. I archive my digital photos to DVD. I store these in a dark, cool place, and again, they are doing fine. My good camera has two SD cards, one of which I have designed as a backup. I have my DVD archive, my Blu-Ray backups, and I archive the SDs when they are full. I think my odds are pretty good. It is getting harder to find DVD and Blu-Ray discs in stores. The next time I order DVDs, it will be online, and I will order archival quality. -- Howard Gibson hgibson@eol.ca jhowardgibson@gmail.com http://home.eol.ca/~hgibson