File span efficiency calculator

[chaynik]

This is somewhat off-topic, but I thought I'd try my luck here :)

I have a collection of rather large files/directories (ranging anywhere from 40GB-200GB per file) that I need to span across a set of disks (or tapes) of fixed size (in this case 800GB). The trick is, I want to span these efficiently so the least amount of space is available on each disk/tape (thus minimizing wasted space). I'm looking for some sort of tool/calculator/script where I can input the file sizes (or preferably it can scan a directory) and it can output the most effective way to span them (tape1: files B+U+Z+Q, tape2: files A+F+L+Z, tape3: files P+G+M, etc) Does such a thing exist?

Thank you in advance.

[trolltuning]

Sounds like a problem for Quattro Pro s optimizer or Excel's solver.

[chaynik]

Thank you for the reply. Could you be more specific on how I could use Excel's solver for this?

[trolltuning]

I am more of a Quattropro person. If you want to pm me the info I will try to run it in optimizer for you.

[kieranrk]

I could probably solve this with LINDO too provided there aren't too many variables.

[trolltuning]

OK I played around with this in Excel
Directions:
Place all the size values in a column
Set up a column of variables with the same no of variables as you have of size values
seed the column with 1's and 0's
set up a 3rd column multiplying the other two columns together
Sum this 3rd column (this is the solution cell for solver)
open up the solver from the tools menu. If you don't see it click on addins and install it
Enter the solution cell and set target to say 830,000,000
Enter the variable cells into solver
Add the following constraints for each variable cell:
<=1,>=0,Integer (in Excel you could skip the >=0 by telling it not to allow neg numbers but you need ths if using the optimizer in Quattropro
set time to 7000
set tolerance to 14%
leave precision alone
click solve
variable cells will contain fractional values, change them to either 1 or 0 whichever is closer
Remove the files that you used for the 1st disk (the ones in the summed column with non zero values) and repeat with the files you have left over. Do this for each disk.

[Didée]

You might have a look at the tool "Burn to the brim". It's made for exactly this purpose ... though, its normal application range is CD / DVD sizes, IIRC. Can't tell if BttB can manage such multi-GB sizes.