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| author | oetiker <oetiker@a5681a0c-68f1-0310-ab6d-d61299d08faa> | |
| Sat, 21 Feb 2009 09:43:58 +0000 (09:43 +0000) | ||
| committer | oetiker <oetiker@a5681a0c-68f1-0310-ab6d-d61299d08faa> | |
| Sat, 21 Feb 2009 09:43:58 +0000 (09:43 +0000) |
diff --git a/doc/bin_dec_hex.pod b/doc/bin_dec_hex.pod
index 743c63d876ea103da69749cd93b713bed96b2eb7..5d3d925c879a075f5c8fe9241265745da2a77eeb 100644 (file)
--- a/doc/bin_dec_hex.pod
+++ b/doc/bin_dec_hex.pod
basic questions. They will not only get their answer, but at the same
time learn a whole lot more.
-Alex van den Bogaerdt E<lt>alex@ergens.op.het.netE<gt>
+Alex van den Bogaerdt E<lt>alex@vandenbogaerdt.nlE<gt>
diff --git a/doc/cdeftutorial.pod b/doc/cdeftutorial.pod
index 72d18070f2c2a5462e4f091a1f381c9817fbed58..1c17046c64c047afcbc5e6dfc4ebc047d1504388 100644 (file)
--- a/doc/cdeftutorial.pod
+++ b/doc/cdeftutorial.pod
to add it. I will then try to provide an answer in the next release
of this tutorial. No feedback equals no changes! Additions to
this document are also welcome. -- Alex van den Bogaerdt
-E<lt>alex@ergens.op.het.netE<gt>
+E<lt>alex@vandenbogaerdt.nlE<gt>
=head2 Why this tutorial?
other people on the RRDtool mailing list. Please let me know if you
find errors in it or if you have trouble understanding it. If you
think there should be an addition, mail me:
-E<lt>alex@ergens.op.het.netE<gt>
+E<lt>alex@vandenbogaerdt.nlE<gt>
Remember: B<No feedback equals no changes!>
=head1 AUTHOR
Alex van den Bogaerdt
-E<lt>alex@ergens.op.het.netE<gt>
+E<lt>alex@vandenbogaerdt.nlE<gt>
diff --git a/doc/rrdgraph.pod b/doc/rrdgraph.pod
index 598e9979655f6868339e39727bcd684c835ead8f..0ac2fbf786798118dcc1ae0299b6b36b51ae5218 100644 (file)
--- a/doc/rrdgraph.pod
+++ b/doc/rrdgraph.pod
Program by Tobias Oetiker E<lt>tobi@oetiker.chE<gt>
-This manual page by Alex van den Bogaerdt E<lt>alex@ergens.op.het.netE<gt>
+This manual page by Alex van den Bogaerdt E<lt>alex@vandenbogaerdt.nlE<gt>
+with corrections and/or additions by several people
diff --git a/doc/rrdgraph_data.pod b/doc/rrdgraph_data.pod
index fc0c2fc360669ed788e20042f7ad92ae9ace4c45..95b1ec70bb45a6f379ac500fa0df2519f866a890 100644 (file)
--- a/doc/rrdgraph_data.pod
+++ b/doc/rrdgraph_data.pod
Program by Tobias Oetiker E<lt>tobi@oetiker.chE<gt>
-This manual page by Alex van den Bogaerdt E<lt>alex@ergens.op.het.netE<gt>
+This manual page by Alex van den Bogaerdt E<lt>alex@vandenbogaerdt.nlE<gt>
+with corrections and/or additions by several people
index 5821438cd417d5e804ef0e9a1bc90ce85f795ba8..b544275f0108c89d07f836d3e3aa61dacc4c1a11 100644 (file)
Program by Tobias Oetiker E<lt>tobi@oetiker.chE<gt>
-This manual page by Alex van den Bogaerdt E<lt>alex@ergens.op.het.netE<gt>
+This manual page by Alex van den Bogaerdt E<lt>alex@vandenbogaerdt.nlE<gt>
+with corrections and/or additions by several people
diff --git a/doc/rrdgraph_graph.pod b/doc/rrdgraph_graph.pod
index e4c284ab35400e73cf119b12ca871d1c7c205f5e..fed1d438278989f394213268ee56591b8202944d 100644 (file)
--- a/doc/rrdgraph_graph.pod
+++ b/doc/rrdgraph_graph.pod
Program by Tobias Oetiker E<lt>tobi@oetiker.chE<gt>
-This manual page by Alex van den Bogaerdt E<lt>alex@ergens.op.het.netE<gt>
+This manual page by Alex van den Bogaerdt E<lt>alex@vandenbogaerdt.nlE<gt>
+with corrections and/or additions by several people
diff --git a/doc/rrdgraph_rpn.pod b/doc/rrdgraph_rpn.pod
index b6b68e3e3b3dec1fb33d7a0ee432a23c13228058..2e29112ee785be2deea4c29041d920a170e26a99 100644 (file)
--- a/doc/rrdgraph_rpn.pod
+++ b/doc/rrdgraph_rpn.pod
Program by Tobias Oetiker E<lt>tobi@oetiker.chE<gt>
-This manual page by Alex van den Bogaerdt E<lt>alex@ergens.op.het.netE<gt>
+This manual page by Alex van den Bogaerdt E<lt>alex@vandenbogaerdt.nlE<gt>
+with corrections and/or additions by several people
diff --git a/doc/rrdresize.pod b/doc/rrdresize.pod
index 917f3fe14e5b789f88197b83d39b3522e6699ec8..af285a5a60309109bc69abefd31309842051196f 100644 (file)
--- a/doc/rrdresize.pod
+++ b/doc/rrdresize.pod
=head1 AUTHOR
-Alex van den Bogaerdt <alex@ergens.op.het.net>
+Alex van den Bogaerdt <alex@vandenbogaerdt.nl>
diff --git a/doc/rrdtutorial.es.pod b/doc/rrdtutorial.es.pod
index 16173f0d2d89037f7ef983437908ddb3fe1f76c0..5402f0395ea2bb6824c7cc57744e8de95f723324 100644 (file)
--- a/doc/rrdtutorial.es.pod
+++ b/doc/rrdtutorial.es.pod
hagan preguntas básicas. No sólo obtendrán la respuesta, sino que
aprenderán muchas otras cosas.
-Alex van den Bogaerdt <alex@ergens.op.het.net>
+¡No hablo español!
+Alex van den Bogaerdt <alex@vandenbogaerdt.nl>
+
diff --git a/doc/rrdtutorial.pod b/doc/rrdtutorial.pod
index 10e414f084b690ff98f44172bc775b09305e20fb..6651a809304d8b38463473197480c1ac15154753 100644 (file)
--- a/doc/rrdtutorial.pod
+++ b/doc/rrdtutorial.pod
+=for changes please consult me first. Thanks, Alex
=head1 NAME
rrdtutorial - Alex van den Bogaerdt's RRDtool tutorial
RRDtool is written by Tobias Oetiker E<lt>tobi@oetiker.chE<gt> with
contributions from many people all around the world. This document is
-written by Alex van den Bogaerdt E<lt>alex@ergens.op.het.netE<gt> to help you
+written by Alex van den Bogaerdt E<lt>alex@vandenbogaerdt.nlE<gt> to help you
understand what RRDtool is and what it can do for you.
The documentation provided with RRDtool can be too technical for some
document explains the basics and may be boring. But if you don't
understand the basics, the examples will not be as meaningful to you.
+Sometimes things change. This example used to provide numbers like
+"0.04" in stead of "4.00000e-02". Those are really the same numbers,
+just written down differently. Don't be alarmed if a future version
+of rrdtool displays a slightly different form of output. The examples
+in this document are correct for version 1.2.0 of RRDtool.
+
+Also, sometimes bugs do occur. They may also influence the outcome of
+the examples. Example speed4.png was suffering from this (the handling
+of unknown data in an if-statement was wrong). Normal data will be
+just fine (a bug in rrdtool wouldn't last long) but special cases like
+NaN, INF and so on may last a bit longer. Try another version if you
+can, or just live with it.
+
+I fixed the speed4.png example (and added a note). There may be other
+examples which suffer from the same or a similar bug. Try to fix it
+yourself, which is a great excercise. But please do not submit your
+result as a fix to the source of this document. Discuss it on the
+user's list, or write to me.
+
=head2 What is RRDtool?
RRDtool refers to Round Robin Database tool.
Round robin is a technique that works with a fixed amount of data, and a
pointer to the current element. Think of a circle with some dots plotted
-on the edge -- these dots are the places where data can be stored. Draw an
-arrow from the center of the circle to one of the dots -- this is the pointer.
+on the edge. These dots are the places where data can be stored. Draw an
+arrow from the center of the circle to one of the dots; this is the pointer.
When the current data is read or written, the pointer moves to the next
element. As we are on a circle there is neither a beginning nor an end, you can
go on and on and on. After a while, all the available places will be used and
=head2 What data can be put into an RRD?
-You name it, it will probably fit as long as it is some sort of time-series
-data. This means you have to be able to measure some value at several points in time and
-provide this information to RRDtool. If you can do this, RRDtool will be
-able to store it. The values must be numerical but don't have to be
-integers, as is the case with MRTG (the next section will give more details
-on this more specialized application).
+You name it, it will probably fit as long as it is some sort of
+time-series data. This means you have to be able to measure some value
+at several points in time and provide this information to RRDtool. If
+you can do this, RRDtool will be able to store it. The values must be
+numerical but don't have to be integers, as is the case with MRTG (the
+next section will give more details on this more specialized application).
Many examples below talk about SNMP which is an acronym for Simple Network
-Management Protocol. "Simple" refers to the protocol -- it does not
+Management Protocol. "Simple" refers to the protocol. It does not
mean it is simple to manage or monitor a network. After working your
way through this document, you should know enough to be able to
understand what people are talking about. For now, just realize that
get used to that right away. Assume a byte is eight bits and start to
think in bits not bytes. The counter, however, still counts bytes!
In the SNMP world most of the counters are 32 bits. That means they are
-counting from 0 to 4'294'967'295. We will use these values in the examples.
+counting from 0 to 4294967295. We will use these values in the examples.
The device, when asked, returns the current value of the counter. We
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
most into miles per hour by dividing km by 1.6 (close enough).
I will use the following abbreviations:
- M: meter
- KM: kilometer (= 1'000 meters).
- H: hour
- S: second
- KM/H: kilometers per hour
- M/S: meters per second
+ m: meter
+ km: kilometer (= 1000 meters).
+ h: hour
+ s: second
+ km/h: kilometers per hour
+ m/s: meters per second
You are driving a car. At 12:05 you read the counter in the dashboard
-and it tells you that the car has moved 12'345 KM until that moment.
-At 12:10 you look again, it reads 12'357 KM. This means you have
-traveled 12 KM in five minutes. A scientist would translate that
+and it tells you that the car has moved 12345 km until that moment.
+At 12:10 you look again, it reads 12357 km. This means you have
+traveled 12 km in five minutes. A scientist would translate that
into meters per second and this makes a nice comparison toward the
problem of (bytes per five minutes) versus (bits per second).
-We traveled 12 kilometers which is 12'000 meters. We did that in five
-minutes or 300 seconds. Our speed is 12'000M / 300S or 40 M/S.
+We traveled 12 kilometers which is 12000 meters. We did that in five
+minutes or 300 seconds. Our speed is 12000m / 300s or 40 m/s.
-We could also calculate the speed in KM/H: 12 times 5 minutes
-is an hour, so we have to multiply 12 KM by 12 to get 144 KM/H.
-For our native English speaking friends: that's 90 MPH so don't
+We could also calculate the speed in km/h: 12 times 5 minutes
+is an hour, so we have to multiply 12 km by 12 to get 144 km/h.
+For our native English speaking friends: that's 90 mph so don't
try this example at home or where I live :)
Remember: these numbers are averages only. There is no way to figure out
from the numbers, if you drove at a constant speed. There is an example
later on in this tutorial that explains this.
-I hope you understand that there is no difference in calculating M/S or
-bps; only the way we collect the data is different. Even the K from kilo
-is the same as in networking terms k also means 1'000.
+I hope you understand that there is no difference in calculating m/s or
+bps; only the way we collect the data is different. Even the k from kilo
+is the same as in networking terms k also means 1000.
We will now create a database where we can keep all these interesting
numbers. The method used to start the program may differ slightly from
We created the round robin database called test (test.rrd) which starts at
noon the day I started writing this document, 7th of March, 1999 (this date
-translates to 920'804'400 seconds as explained below). Our database holds
+translates to 920804400 seconds as explained below). Our database holds
one data source (DS) named "speed" that represents a counter. This counter
is read every five minutes (this is the default therefore you don't have to
put C<--step=300>). In the same database two round robin archives (RRAs)
We now have to fill our database with some numbers. We'll pretend to
have read the following numbers:
- 12:05 12345 KM
- 12:10 12357 KM
- 12:15 12363 KM
- 12:20 12363 KM
- 12:25 12363 KM
- 12:30 12373 KM
- 12:35 12383 KM
- 12:40 12393 KM
- 12:45 12399 KM
- 12:50 12405 KM
- 12:55 12411 KM
- 13:00 12415 KM
- 13:05 12420 KM
- 13:10 12422 KM
- 13:15 12423 KM
+ 12:05 12345 km
+ 12:10 12357 km
+ 12:15 12363 km
+ 12:20 12363 km
+ 12:25 12363 km
+ 12:30 12373 km
+ 12:35 12383 km
+ 12:40 12393 km
+ 12:45 12399 km
+ 12:50 12405 km
+ 12:55 12411 km
+ 13:00 12415 km
+ 13:05 12420 km
+ 13:10 12422 km
+ 13:15 12423 km
We fill the database as follows:
writes "U" or "UNKN" or something similar that's okay. If something
else is wrong, it will probably be due to an error you made (assuming
that my tutorial is correct of course :-). In that case: delete the
-database and try again. Sometimes things change. This example used
-to provide numbers like "0.04" in stead of "4.00000e-02". Those are
-really the same numbers, just written down differently. Don't be
-alarmed if a future version of rrdtool displays a slightly different
-form of output. The examples in this document are correct for version
-1.2.0 of RRDtool.
+database and try again.
+
The meaning of the above output will become clear below.
magenta #FF00FF (mixed red with blue)
gray #555555 (one third of all components)
-Additionally you can add an alpha channel (transparency). The default
-will be "FF" which means non-transparent.
+Additionally you can (with a recent RRDtool) add an alpha channel
+(transparency). The default will be "FF" which means non-transparent.
The PNG you just created can be displayed using your favorite image
viewer. Web browsers will display the PNG via the URL
When looking at the image, you notice that the horizontal axis is labeled
12:10, 12:20, 12:30, 12:40 and 12:50. Sometimes a label doesn't fit (12:00
-and 13:00 would be candidates) so they are skipped.
+and 13:00 would be likely candidates) so they are skipped.
The vertical axis displays the range we entered. We provided
kilometers and when divided by 300 seconds, we get very small
-numbers. To be exact, the first value was 12 (12'357-12'345) and divided
+numbers. To be exact, the first value was 12 (12357-12345) and divided
by 300 this makes 0.04, which is displayed by RRDtool as "40 m"
-meaning "40/1'000". The "m" (milli) has nothing to do with meters,
+meaning "40/1000". The "m" (milli) has nothing to do with meters (also m),
kilometers or millimeters! RRDtool doesn't know about the physical
units of our data, it just works with dimensionless numbers.
If we had measured our distances in meters, this would have been
-(12'357'000-12'345'000)/300 = 12'000/300 = 40.
+(12357000-12345000)/300 = 12000/300 = 40.
As most people have a better feel for numbers in this range, we'll
correct that. We could recreate our database and store the correct
CDEF:realspeed=myspeed,1000,\* \
LINE2:realspeed#FF0000
-Note: Make sure not to forget the backslash \ in front of the
-multiplication operator * above. The backslash is needed to "escape"
-the * as some operating systems might interpret and expand * instead
-of passing it to the rrdtool command.
+Note: I need to escape the multiplication operator * with a backslash.
+If I don't, the operating system may interpret it and use it for file
+name expansion. You could also place the line within quotation marks
+like so:
+
+ "CDEF:realspeed=myspeed,1000,*" \
+
+It boils down to: it is RRDtool which should see *, not your shell.
+And it is your shell interpreting \, not RRDtool. You may need to
+adjust examples accordingly if you happen to use an operating
+system or shell which behaves differently.
After viewing this PNG, you notice the "m" (milli) has
disappeared. This it what the correct result would be. Also, a label
more detail. Also, you may want to read my tutorial on CDEFs and Steve
Rader's tutorial on RPN. But first finish this tutorial.
-Hang on! If we can multiply values with 1'000, it should also be possible
+Hang on! If we can multiply values with 1000, it should also be possible
to display kilometers per hour from the same data!
To change a value that is measured in meters per second:
- Calculate meters per hour: value * 3'600
- Calculate kilometers per hour: value / 1'000
- Together this makes: value * (3'600/1'000) or value * 3.6
+ Calculate meters per hour: value * 3600
+ Calculate kilometers per hour: value / 1000
+ Together this makes: value * (3600/1000) or value * 3.6
In our example database we made a mistake and we need to compensate for
-this by multiplying with 1'000. Applying that correction:
+this by multiplying with 1000. Applying that correction:
- value * 3.6 * 1'000 == value * 3'600
+ value * 3.6 * 1000 == value * 3600
Now let's create this PNG, and add some more magic ...
Note: here we use another means to escape the * operator by enclosing
the whole string in double quotes.
-This graph looks much better. Speed is shown in KM/H and there is even
+This graph looks much better. Speed is shown in km/h and there is even
an extra line with the maximum allowed speed (on the road I travel
on). I also changed the colors used to display speed and changed it
from a line into an area.
--start 920804400 --end 920808000 \
--vertical-label km/h \
DEF:myspeed=test.rrd:speed:AVERAGE \
- "CDEF:kmh=myspeed,3600,*" \
+ CDEF:nonans=myspeed,UN,0,myspeed,IF \
+ CDEF:kmh=nonans,3600,* \
CDEF:fast=kmh,100,GT,100,0,IF \
CDEF:over=kmh,100,GT,kmh,100,-,0,IF \
CDEF:good=kmh,100,GT,0,kmh,IF \
AREA:fast#550000:"Too fast" \
STACK:over#FF0000:"Over speed"
+Remember the note in the beginning? I had to remove unknown data from
+this example. The 'nonans' CDEF is new, and the 6th line (which used to
+be the 5th line) used to read 'CDEF:kmh=myspeed,3600,*'
+
Let's create a quick and dirty HTML page to view the three PNGs:
<HTML><HEAD><TITLE>Speed</TITLE></HEAD><BODY>
the stuff you learned so far. Later on we will also be able to monitor
other types of values like temperature.
-Most (?) people interested in RRDtool will use the counter that keeps track
+Many people interested in RRDtool will use the counter that keeps track
of octets (bytes) transfered by a network device. So let's do just
that next. We will start with a description of how to collect data.
LINE1:outoctets#0000FF:"Out traffic"
This should produce a picture with one day worth of traffic.
-One day is 24 hours of 60 minutes of 60 seconds: 24*60*60=86'400, we
-start at now minus 86'400 seconds. We define (with DEFs) inoctets and
+One day is 24 hours of 60 minutes of 60 seconds: 24*60*60=86400, we
+start at now minus 86400 seconds. We define (with DEFs) inoctets and
outoctets as the average values from the database myrouter.rrd and draw
an area for the "in" traffic and a line for the "out" traffic.
into this a bit more.
Recall all the stuff about the speed of the car. Suppose we drove at 144
-KM/H during 5 minutes and then were stopped by the police for 25 minutes.
+km/h during 5 minutes and then were stopped by the police for 25 minutes.
At the end of the lecture we would take our laptop and create and view the
image taken from the database. If we look at the second RRA we did
create, we would have the average from 6 samples. The samples measured
would be 144+0+0+0+0+0=144, divided by 30 minutes, corrected for the
-error by 1000, translated into KM/H, with a result of 24 KM/H.
+error by 1000, translated into km/h, with a result of 24 km/h.
I would still get a ticket but not for speeding anymore :)
Obviously, in this case we shouldn't look at the averages. In some
-cases they are handy. If you want to know how many KM you had traveled,
+cases they are handy. If you want to know how many km you had traveled,
the averaged picture would be the right one to look at. On the other hand, for
the speed that we traveled at, the maximum numbers seen is much more
interesting. Later we will see more types.
archive that keeps averages will show low numbers, the archive that
shows maxima will have higher numbers.
-For my car this would translate in averages per day of 96/24=4 KM/H
+For my car this would translate in averages per day of 96/24=4 km/h
(as I travel about 94 kilometers on a day) during working days, and
-maxima of 120 KM/H (my top speed that I reach every day).
+maxima of 120 km/h (my top speed that I reach every day).
Big difference. Do not look at the second graph to estimate the
distances that I travel and do not look at the first graph to
as they are in five minutes, but not if you average.
On some days, I go for a long ride. If I go across Europe and travel
-for 12 hours, the first graph will rise to about 60 KM/H. The second
-one will show 180 KM/H. This means that I traveled a distance of 60
-KM/H times 24 H = 1440 KM. I did this with a higher speed and a
-maximum around 180 KM/H. However, it probably doesn't mean that I
-traveled for 8 hours at a constant speed of 180 KM/H!
+for 12 hours, the first graph will rise to about 60 km/h. The second
+one will show 180 km/h. This means that I traveled a distance of 60
+km/h times 24 h = 1440 km. I did this with a higher speed and a
+maximum around 180 km/h. However, it probably doesn't mean that I
+traveled for 8 hours at a constant speed of 180 km/h!
This is a real example: go with the flow through Germany (fast!) and stop
a few times for gas and coffee. Drive slowly through Austria and the
counter with one difference: RRDtool assumes the counter is reset when
it's read. That is: its delta is known without calculation by RRDtool
whereas RRDtool needs to calculate it for the counter type.
-Example: our first example (12'345, 12'357, 12'363, 12'363) would read:
+Example: our first example (12345, 12357, 12363, 12363) would read:
unknown, 12, 6, 0. The rest of the calculations stay the same.
The other one, derive, is like counter. Unlike counter, it can also
decrease so it can have a negative delta. Again, the rest of the
=item *
Line C is of type DERIVE. It should be a counter that can decrease. It does
-so between 2'400 and 0, with 1'800 in-between.
+so between 2400 and 0, with 1800 in-between.
=item *
There are a few more basics to show. Some important options are still to
be covered and we haven't look at counter wraps yet. First the counter wrap:
-In our car we notice that the counter shows 999'987. We travel 20 KM and
-the counter should go to 1'000'007. Unfortunately, there are only six digits
-on our counter so it really shows 000'007. If we would plot that on a type
-DERIVE, it would mean that the counter was set back 999'980 KM. It wasn't,
+In our car we notice that the counter shows 999987. We travel 20 km and
+the counter should go to 1000007. Unfortunately, there are only six digits
+on our counter so it really shows 000007. If we would plot that on a type
+DERIVE, it would mean that the counter was set back 999980 km. It wasn't,
and there has to be some protection for this. This protection is only
available for type COUNTER which should be used for this kind of counter
anyways. How does it work? Type counter should never decrease and
If the delta is negative, this can be compensated for by adding the
maximum value of the counter + 1. For our car this would be:
- Delta = 7 - 999'987 = -999'980 (instead of 1'000'007-999'987=20)
+ Delta = 7 - 999987 = -999980 (instead of 1000007-999987=20)
- Real delta = -999'980 + 999'999 + 1 = 20
+ Real delta = -999980 + 999999 + 1 = 20
At the time of writing this document, RRDtool knows of counters that
are either 32 bits or 64 bits of size. These counters can handle the
following different values:
- - 32 bits: 0 .. 4'294'967'295
- - 64 bits: 0 .. 18'446'744'073'709'551'615
+ - 32 bits: 0 .. 4294967295
+ - 64 bits: 0 .. 18446744073709551615
If these numbers look strange to you, you can view them in
their hexadecimal form:
Correction numbers:
- - 32 bits: (4'294'967'295 + 1) = 4'294'967'296
- - 64 bits: (18'446'744'073'709'551'615 + 1)
- - correction1 = 18'446'744'069'414'584'320
+ - 32 bits: (4294967295 + 1) = 4294967296
+ - 64 bits: (18446744073709551615 + 1)
+ - correction1 = 18446744069414584320
- Before: 4'294'967'200
+ Before: 4294967200
Increase: 100
- Should become: 4'294'967'300
+ Should become: 4294967300
But really is: 4
- Delta: -4'294'967'196
- Correction1: -4'294'967'196 + 4'294'967'296 = 100
+ Delta: -4294967196
+ Correction1: -4294967196 + 4294967296 = 100
- Before: 18'446'744'073'709'551'000
+ Before: 18446744073709551000
Increase: 800
- Should become: 18'446'744'073'709'551'800
+ Should become: 18446744073709551800
But really is: 184
- Delta: -18'446'744'073'709'550'816
- Correction1: -18'446'744'073'709'550'816
- + 4'294'967'296 = -18'446'744'069'414'583'520
- Correction2: -18'446'744'069'414'583'520
- + 18'446'744'069'414'584'320 = 800
-
- Before: 18'446'744'073'709'551'615 ( maximum value )
- Increase: 18'446'744'069'414'584'320 ( absurd increase, minimum for
- Should become: 36'893'488'143'124'135'935 this example to work )
- But really is: 18'446'744'069'414'584'319
- Delta: -4'294'967'296
- Correction1: -4'294'967'296 + 4'294'967'296 = 0
+ Delta: -18446744073709550816
+ Correction1: -18446744073709550816
+ + 4294967296 = -18446744069414583520
+ Correction2: -18446744069414583520
+ + 18446744069414584320 = 800
+
+ Before: 18446744073709551615 ( maximum value )
+ Increase: 18446744069414584320 ( absurd increase, minimum for
+ Should become: 36893488143124135935 this example to work )
+ But really is: 18446744069414584319
+ Delta: -4294967296
+ Correction1: -4294967296 + 4294967296 = 0
(not negative -> no correction2)
- Before: 18'446'744'073'709'551'615 ( maximum value )
- Increase: 18'446'744'069'414'584'319 ( one less increase )
- Should become: 36'893'488'143'124'135'934
- But really is: 18'446'744'069'414'584'318
- Delta: -4'294'967'297
- Correction1: -4'294'967'297 + 4'294'967'296 = -1
- Correction2: -1 + 18'446'744'069'414'584'320 = 18'446'744'069'414'584'319
+ Before: 18446744073709551615 ( maximum value )
+ Increase: 18446744069414584319 ( one less increase )
+ Should become: 36893488143124135934
+ But really is: 18446744069414584318
+ Delta: -4294967297
+ Correction1: -4294967297 + 4294967296 = -1
+ Correction2: -1 + 18446744069414584320 = 18446744069414584319
As you can see from the last two examples, you need strange numbers
for RRDtool to fail (provided it's bug free of course), so this should
time+600: 600 delta=300 time+603: 603 delta=303
time+900: 900 delta=300 time+900: 900 delta=297
-Let's create two identical databases. I've chosen the time range 920'805'000
-to 920'805'900 as this goes very well with the example numbers.
+Let's create two identical databases. I've chosen the time range 920805000
+to 920805900 as this goes very well with the example numbers.
rrdtool create seconds1.rrd \
--start 920804700 \
time learn a whole lot more.
Alex van den Bogaerdt
-E<lt>alex@ergens.op.het.netE<gt>
+E<lt>alex@vandenbogaerdt.nlE<gt>