Regarding slide 27, if I'm reading and calculating correctly, 'n' doesn't represent the number of drives of usable space desired. I think 2^n does. I don't know how to reword it. In the examples given, 'n' is an to an index that increases from 1 to whatever such that
If I, for instance, want 4 usable drives (my current setup), N = 2. 2^N would be 4, then 2 for parity (zraid2) = 6 drives. I did try to figure out the formula for deriving "n" based on number of desired drives, but I gave up. The inverse of an y-eponential is a y-root, but I couldn't finish it out. The best I could come up with is to use the table your formula builds (though 'n' would be an index, not number of desired usable drives). Your usable drives desired needs to be a number after the first equal sign, and your "n" becomes whatever "n" is on the same line.
Sorry I couldn't be more constructive on how to modify it, but I did at least want to point it out.
Code:
1 - 2^1+1=2+1=3 2^1+2=2+2=4 2 - 2^2+1=4+1=5 2^2+2=4+2=6 3 - 2^3+1=8+1=9 2^3+2=8+2=10 4 - 2^4+1=16+1=17 2^4+2=16+2=18 5 - 2^5+1=32+1=33 2^5+2=32+2=34 6 - 2^6+1=64+1=65 2^6+2=64+2=66
If I, for instance, want 4 usable drives (my current setup), N = 2. 2^N would be 4, then 2 for parity (zraid2) = 6 drives. I did try to figure out the formula for deriving "n" based on number of desired drives, but I gave up. The inverse of an y-eponential is a y-root, but I couldn't finish it out. The best I could come up with is to use the table your formula builds (though 'n' would be an index, not number of desired usable drives). Your usable drives desired needs to be a number after the first equal sign, and your "n" becomes whatever "n" is on the same line.
Sorry I couldn't be more constructive on how to modify it, but I did at least want to point it out.