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Example backup schedule
I have mentioned that I found my old backup volume rotation schedule-generating program from back when I had a large stack of such volumes on a shelf. The two variables of interest are how many backup volumes one has and how many rotations' history one may want to go back. To take a simple example, if I have only five volumes A, B, C, D, E for daily backups but want them to include many months' history then I could generate a schedule of,
Implementation note: This example sequence clearly has a three-fold repetition built in. Let us then say that r=3 and, for our five backup volumes, that v=5. The number of rotations' history offered by my program's generated sequences is at most 2×(r+1)(v-2), so 128 for this example.
CAAAEAAAEAAAEAAADAAAEAAAEAAAEAAADAAAEAAAEAAAEAAADAAAEAAAEAAAEAAA DBBBABBBABBBABBBEBBBABBBABBBABBBEBBBABBBABBBABBBEBBBABBBABBBABBB ECCCBCCCBCCCBCCCACCCBCCCBCCCBCCCACCCBCCCBCCCBCCCACCCBCCCBCCCBCCC ADDDCDDDCDDDCDDDBDDDCDDDCDDDCDDDBDDDCDDDCDDDCDDDBDDDCDDDCDDDCDDD BEEEDEEEDEEEDEEECEEEDEEEDEEEDEEECEEEDEEEDEEEDEEECEEEDEEEDEEEDEEEI figured that such an example would help to make the abstract idea clearer. I have no idea how professionals currently achieve such spreads of backup intervals.
Implementation note: This example sequence clearly has a three-fold repetition built in. Let us then say that r=3 and, for our five backup volumes, that v=5. The number of rotations' history offered by my program's generated sequences is at most 2×(r+1)(v-2), so 128 for this example.