Hello,
Does amanda need a minimum number of tapes to finish a dumpcycle of, say, 7
days?
My situation is as follows:
There are two hosts to be backed up, one having a du of 7G and the other 3.5G.
Day to day changes is less than 1% of the total du for each host. I have a
single tape drive with 15G of uncompressed capacity (~30G compressed).
To start, I plan on having a dumpcycle of 7 with a runcycle of 5. Can I set
the tapecycle to 1 (or 2) and still have things backed up properly? The
reason I have this restriction is because the machines in question are at a
colocation facility, so changing tapes everyday is inconvenient at best.
Going by the simple math in the UB&R amanda chapter, I have:
11G / 7 = 1.6G
11G / 7 * 1(.01) = 0.02G
11G / 7 * 2(.01) = 0.03G
11G / 7 * 3(.01) = 0.05G
11G / 7 * 4(.01) = 0.07G
11G / 7 * 5(.01) = 0.08G
11G / 7 * 6(.01) = 0.10G
= 2.0G
I assume that the first run will do a complete level 0 dump, which will be
11G. So over a period of one week, 13G of tape would be used.
Does my math make sense here?
What pitfalls should I expect by using only one tape per week? I've also read
that the tapecyle should be ((Runs + 1) * #tapes), so in my case, this would be
two tapes. So I suppose this means that I should at the least use 2 tapes per
dumpcycle (which is one week)?
Also, by using one (or two) tapes means that amanda has to fit multiple images
onto a single tape. Will this be a problem? How easy is it to recover from a
tape with multiple images?
Thanks for helping a newbie,
Antony
