X-Git-Url: https://git.tokkee.org/?a=blobdiff_plain;f=doc%2Frrdtutorial.html;h=4eda356ae9847c7ca648963508dbc120b2ef6b9f;hb=06ef6a573e296977f34f9153039a377fb96c407b;hp=fc73b900e5fb7d17686c978ccd28018bea406ce9;hpb=1559397b94b4af3de73cfa23c04be31d8bee53e7;p=pkg-rrdtool.git diff --git a/doc/rrdtutorial.html b/doc/rrdtutorial.html index fc73b90..4eda356 100644 --- a/doc/rrdtutorial.html +++ b/doc/rrdtutorial.html @@ -1,9 +1,7 @@ -
+
+rrdtutorial - Alex van den Bogaerdt's RRDtool tutorial
@@ -200,18 +203,17 @@ know the time that has passes since we last asked so we now know how many bytes have been transfered ***on average*** per second. This is not very hard to calculate. First in words, then in calculations:
Take the current counter, subtract the previous value from it.
-Do the same with the current time and the previous time (in seconds).
-Divide the outcome of (1) by the outcome of (2), the result is +
bps = (counter_now - counter_before) / (time_now - time_before) * 8
For some people it may help to translate this to an automobile example. @@ -842,26 +844,25 @@ calculations stay the same.
Line A is a COUNTER type, so it should continuously increment and RRDtool +
Line B is of type GAUGE. These are ``real'' values so they should match -what we put in: a sort of a wave.
-Line C is of type DERIVE. It should be a counter that can decrease. It does -so between 2400 and 0, with 1800 in-between.
-Line D is of type ABSOLUTE. This is like counter but it works on +straight line at 1 (the deltas are 300, the time is 300). +
+This translates in the following values, starting at 23:10 and ending at 00:10 the next day (where ``u'' means unknown/unplotted):
@@ -876,35 +877,34 @@ and you successfully entered the year 2000 :) the lines.Let's go over the data again:
Line A: 300,600,900 and so on. The counter delta is a constant 300 and +
Why is it that the first point is unknown? We do know what we put into the database, right? True, But we didn't have a value to calculate the delta from, so we don't know where we started. It would be wrong to assume we started at zero so we don't!
- -Line B: There is nothing to calculate. The numbers are as they are.
-Line C: Again, the start-out value is unknown. The same story is holds +
+Line D: Here the device calculates the deltas. Therefore we DO know the +this makes a difference. +
+