My oldest file is 1975-06-25. Don't bother. Just buy new disks. Disk capacities double every so often, while being cheaper and more energetically efficient.

My oldest file is 1975-06-25. Don't bother. Just buy new disks. Disk capacities double every so often, while being cheaper and more energetically efficient. Therefore there's no point in spending time sorting out your files, deleting, archiving them. Just copy them to the bigger new disks, and leave them there. Really. At various times I've made archives (gzip'ed tarballs). They amount to an insignificant size compared to the multiple terabytes of storage currently available on my workstation (200 KB(!) + 8 MB(!) + 16 GB). It was really not worth the time of sorting them out and archiving them. Similarly, for backups, I guess it's clear nowadays, that just having various hard disks of the same size and synch'ing them is the most time efficient and safest way to backup. I've spend so much time backuping on various classes of devices (magnetic tapes, optical disks, CDR), they all were time consumming and most of the time, failed to restore correctly at 100%. Hard disk storage is the best, fastest and cheapest. Now of course, nowadays we're switching to SSD, so there's a little price bump compared to magnetic hard disks, and there are still some worrying about the perenity of data on SSD. But the technology improves, and if you can fit in the capacities (for your budget), this can be used as well as hard disks. Just wait for "Her". Then sorting and archiving will be done by your personnal AI in a fraction of second. :-)