[Gllug] Unix dumps and the tower of Hanoi

[James Hawtin]

I have tried to understand this thing however I just don't get it. Why do
Unix people like to use this number sequence for backups?

3, 2, 5, 4, 7, 6, 9,

>From what I can see from reading the dump man page closely an incremental
backup is based on the dumps LESS THAN the current level not less than and
equal too. (If it was I could understand it, as the 3, 2 would force it to
backup all files since the level 0 again rather than basing on the previous
dump, however this is not the case).

The above is functionally the same as:-

2, 2, 3, 3, 4, 4, 5,

The only reason I can think that it is of any use is when each "Number" is a
tape, and it is trying to maximise the versions available on the tapes, not
destroying the previous days backup before it has written the new
one. However it does not say this in the any manual most people don't use
tapes these days anyway... is it just a throw back to the old days of tape 
management?

James
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