Hendrik Boom said on Mon, 1 Nov 2021 08:11:54 -0400
>Now storage media deteriorate over time. >It is necessary to read and transfer data from old media to new from >time to time. Yes, I know that. My present method is to keep >everything on my server, and make regular backups. Backup is, and always has been a problem. I've written several times on the subject: http://troubleshooters.com/tpromag/9807.htm http://troubleshooters.com/lpm/200208/200208.htm http://troubleshooters.com/lpm/200609/200609.htm http://troubleshooters.com/lpm/201406/201406.htm I've discovered that long term restorability depends on several things: * How standard is the backup format? .tgz will be around for decades, Fastback format became almost impossible to read after a decade. * How standard is the backup media? I have some QIC tapes from the mid 90's that I don't even try to read. I have some CPM formatted floppies from 1984 that I'm still trying to find a way to read. Meanwhile, my ISO9660 CDs from the late 1990's, holding 8.3 filename format .tgz files, are trivial to read. * How robust is the backup media? Consumer grade tapes are probably unreadable within a couple years. Some consumer grade tapes are unrestorable one second after making them. Even worse are floppy backups. My experience tells me that flash drives, even if formatted as ext4 instead of that guaranteed data loss Windows format, go bad. USB spinning rust hard drives have so far restored for me, but the whole concept is scary. SSD is too expensive per GB to use for backup. My restorability successes mostly revolve around CD and DVD ISO 9660 holding tarballs in 8.3 format. I keep them in a rolltop box to shelter them from light, and my house is air conditioned, and I see no degradation so far. My results using Blu-Ray are mixed. Some still restore, but some went bad, and I mean visibly bad where you could see discolorations, within a couple years. Anybody whose backups would require less than 5 DVDs, I'd recommend DVDs with ISO9660 8.3 filename tarballs, additionally storing an md5 checksum for each tarball. I've never had an md5 file read differently than the md5 value of the tarball, even after a decade. If more than 5 DVDs worth, it's tougher. I use a combination of UDF formatted Blu-Ray media and USB spinning rust hard drives. I keep most of my backups in a bank safety deposit vault. Try to get a box as high off the ground as you can, to prevent flood damage. HTH, SteveT Steve Litt Spring 2021 featured book: Troubleshooting Techniques of the Successful Technologist http://www.troubleshooters.com/techniques _______________________________________________ Dng mailing list Dng@lists.dyne.org https://mailinglists.dyne.org/cgi-bin/mailman/listinfo/dng
