As a systems administrator (SYSPROG) for mainframe systems since 1974, I understand backups pretty well.
I also know that keeping two copies of pictures on two different hard drives is not adequate.
I know this because I was keeping two copies. Then I found a duplicate file finder application and it found numerous mismatches. I then used d'peg to do a side by side comparison and sure enough, they really were a mismatch. Sometimes it was obvious, where the bottom have lf the picture was either a weir color or right shifted a bit.
This is commonly called bit-rot.
It almost never happens on mainframe systems because they have a lo of CRC (error detection and correction stuff), but it takes up space and consumers don't like spending extra money for reliability. They only want capacity.
I wonder if 3 copies on 3 different hard drives would be adequate. Maybe I switch to RAID and enable striping.
Thanks for pointing out the backup issue. I understand it well, but some other readers may not be familiar with the issue.
After crashing a mainframe operating system, with inadequate backups around 1976, I learned that there is no such thing as too many backups.
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