[smokeping-users] Question about Database Config.

Gregory Sloop gregs at sloop.net
Thu Dec 8 05:07:16 CET 2011


Hey, as long I'm wasting bandwidth... :)

It just occurred to me that my calculations prior on the number of KB
per row(s) was wrong.

The calculation I used was
8.5MB / (4300 + 4300 + 2400) = MB / RRD row

But after looking at the details of the RRD file, it appears I'm
wrong, and the calc should look something like this:

8.5MB / (4300 + (4300*3) + (2400 * 3)) = MB / RRD row

So, provided my new calculations are right, the general rough estimate
for number of rows per MB is really something different.

Also, I'm using 40 pings, rather than 20, so I have twice as many
values as the default.

So, it's probably really something like this
8.5MB / ((4300 + (4300*3) + (2400 * 3)*# of pings)) = MB / RRD row

So, really, my calculations are pretty much bollocks. I'm sure there's
a better formula - but it's probably just a whole heap easier just to
create the dang thing and see how big it is. :)

Which reminds me of that Calvin and Hobbes strip...
http://www.s-anand.net/blog/calvin-and-hobbes-dad-explains-science/

"How do they know the load limit on bridges Dad?”
“They drive bigger and bigger trucks over the bridge until it breaks. Then they weigh the last truck and rebuild the bridge.”
“Oh. I should’ve guessed.

-Greg



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