B<rrdtool> B<create> I<filename>
S<[B<--start>|B<-b> I<start time>]>
S<[B<--step>|B<-s> I<step>]>
-S<[B<DS:>I<ds-name>B<:>I<DST>B<:>I<heartbeat>B<:>I<min>B<:>I<max>]>
+S<[B<DS:>I<ds-name>B<:>I<DST>B<:>I<dst arguments>]>
S<[B<RRA:>I<CF>B<:>I<cf arguments>]>
=head1 DESCRIPTION
=item I<filename>
The name of the B<RRD> you want to create. B<RRD> files should end
-with the extension F<.rrd>. However, B<rrdtool> will accept any
+with the extension F<.rrd>. However, B<RRDtool> will accept any
filename.
=item B<--start>|B<-b> I<start time> (default: now - 10s)
Specifies the time in seconds since 1970-01-01 UTC when the first
-value should be added to the B<RRD>. B<rrdtool> will not accept
+value should be added to the B<RRD>. B<RRDtool> will not accept
any data timed before or at the time specified.
See also AT-STYLE TIME SPECIFICATION section in the
Specifies the base interval in seconds with which data will be fed
into the B<RRD>.
-=item B<DS:>I<ds-name>B<:>I<DST>B<:>I<heartbeat>B<:>I<min>B<:>I<max>
+=item B<DS:>I<ds-name>B<:>I<DST>B<:>I<dst arguments>
A single B<RRD> can accept input from several data sources (B<DS>).
(e.g. Incoming and Outgoing traffic on a specific communication
source from an B<RRD>. A I<ds-name> must be 1 to 19 characters long in
the characters [a-zA-Z0-9_].
-I<DST> defines the Data Source Type. See the section on "How to Measure" below for further insight.
-The Datasource Type must be onw of the following:
+I<DST> defines the Data Source Type. The remaining arguments of a
+data source entry depend upon the data source type. For GAUGE, COUNTER,
+DERIVE, and ABSOLUTE the format for a data source entry is:
+
+B<DS:>I<ds-name>B<:>I<GAUGE | COUNTER | DERIVE | ABSOLUTE>B<:>I<heartbeat>B<:>I<min>B<:>I<max>
+
+For COMPUTE data sources, the format is:
+
+B<DS:>I<ds-name>B<:>I<COMPUTE>B<:>I<rpn-expression>
+
+To decide on a data source type, review the definitions that follow.
+Consult the section on "HOW TO MEASURE" for further insight.
=over 4
=item B<COUNTER>
is for continuous incrementing counters like the
-InOctets counter in a router. The B<COUNTER> data source assumes that
+ifInOctets counter in a router. The B<COUNTER> data source assumes that
the counter never decreases, except when a counter overflows. The update
function takes the overflow into account. The counter is stored as a
per-second rate. When the counter overflows, RRDtool checks if the overflow happened at
will store the derivative of the line going from the last to the
current value of the data source. This can be useful for gauges, for
example, to measure the rate of people entering or leaving a
-room. Internally, derive works exaclty like COUNTER but without
+room. Internally, derive works exactly like COUNTER but without
overflow checks. So if your counter does not reset at 32 or 64 bit you
might want to use DERIVE and combine it with a MIN value of 0.
next overflow. Another usage is for things you count like number of messages
since the last update.
+=item B<COMPUTE>
+
+is for storing the result of a formula applied to other data sources in
+the B<RRD>. This data source is not supplied a value on update, but rather
+its Primary Data Points (PDPs) are computed from the PDPs of the data sources
+according to the rpn-expression that defines the formula. Consolidation
+functions are then applied normally to the PDPs of the COMPUTE data source
+(that is the rpn-expression is only applied to generate PDPs). In database
+software, these are referred to as "virtual" or "computed" columns.
+
=back
I<heartbeat> defines the maximum number of seconds that may pass
always set the min and/or max properties. This will help RRDtool in
doing a simple sanity check on the data supplied when running update.>
+I<rpn-expression> defines the formula used to compute the PDPs of a COMPUTE
+data source from other data sources in the same <RRD>. It is similar to defining
+a B<CDEF> argument for the graph command. Please refer to that manual page
+for a list and description of RPN operations supported. For
+COMPUTE data sources, the following RPN operations are not supported: COUNT, PREV,
+TIME, and LTIME. In addition, in defining the RPN expression, the COMPUTE
+data source may only refer to the names of data source listed previously
+in the create command. This is similar to the restriction that B<CDEF>s must
+refer only to B<DEF>s and B<CDEF>s previously defined in the same graph command.
+
=item B<RRA:>I<CF>B<:>I<cf arguments>
-
+
+
The purpose of an B<RRD> is to store data in the round robin archives
(B<RRA>). An archive consists of a number of data values or statistics for
each of the defined data-sources (B<DS>) and is defined with an B<RRA> line.
The data is also processed with the consolidation function (I<CF>)
of the archive. There are several consolidation functions that consolidate
primary data points via an aggregate function: B<AVERAGE>, B<MIN>, B<MAX>, B<LAST>.
-The format of B<RRA> line for these consolidation function is:
+The format of B<RRA> line for these consolidation functions is:
B<RRA:>I<AVERAGE | MIN | MAX | LAST>B<:>I<xff>B<:>I<steps>B<:>I<rows>
=back
-=head1 Aberrant Behaviour detection with Holt-Winters forecasting
+=head1 Aberrant Behavior Detection with Holt-Winters Forecasting
by Jake Brutlag E<lt>jakeb@corp.webtv.netE<gt>
=over 4
-=item B<RRA:>I<HWPREDICT>B<:>I<rows>B<:>I<alpha>B<:>I<beta>B<:>I<seasonal period>B<:>I<rra num>
+=item B<RRA:>I<HWPREDICT>B<:>I<rows>B<:>I<alpha>B<:>I<beta>B<:>I<seasonal period>B<:>I<rra-num>
-=item B<RRA:>I<SEASONAL>B<:>I<seasonal period>B<:>I<gamma>B<:>I<rra num>
+=item B<RRA:>I<SEASONAL>B<:>I<seasonal period>B<:>I<gamma>B<:>I<rra-num>
-=item B<RRA:>I<DEVSEASONAL>B<:>I<seasonal period>B<:>I<gamma>B<:>I<rra num>
+=item B<RRA:>I<DEVSEASONAL>B<:>I<seasonal period>B<:>I<gamma>B<:>I<rra-num>
-=item B<RRA:>I<DEVPREDICT>B<:>I<rows>B<:>I<rra num>
+=item B<RRA:>I<DEVPREDICT>B<:>I<rows>B<:>I<rra-num>
-=item B<RRA:>I<FAILURES>B<:>I<rows>B<:>I<threshold>B<:>I<window length>B<:>I<rra num>
+=item B<RRA:>I<FAILURES>B<:>I<rows>B<:>I<threshold>B<:>I<window length>B<:>I<rra-num>
=back
appears in L<rrdgraph>.
The SEASONAL and DEVSEASONAL B<RRAs> store the seasonal coefficients for the
-Holt-Winters Forecasting algorithm and the seasonal deviations respectively.
+Holt-Winters forecasting algorithm and the seasonal deviations respectively.
There is one entry per observation time point in the seasonal cycle. For
example, if primary data points are generated every five minutes, and the
seasonal cycle is 1 day, both SEASONAL and DEVSEASONAL with have 288 rows.
In order to simplify the creation for the novice user, in addition to
supporting explicit creation the HWPREDICT, SEASONAL, DEVPREDICT,
-DEVSEASONAL, and FAILURES B<RRAs>, the B<rrdtool> create command supports
+DEVSEASONAL, and FAILURES B<RRAs>, the B<RRDtool> create command supports
implicit creation of the other four when HWPREDICT is specified alone and
-the final argument I<rra num> is omitted.
+the final argument I<rra-num> is omitted.
I<rows> specifies the length of the B<RRA> prior to wrap around. Remember
that there is a one-to-one correspondence between primary data points and
entries in these RRAs. For the HWPREDICT CF, I<rows> should be larger than
-the I<seasonal period>. If the DEVPREDICT B<RRA> is implicity created, the
+the I<seasonal period>. If the DEVPREDICT B<RRA> is implicitly created, the
default number of rows is the same as the HWPREDICT I<rows> argument. If the
FAILURES B<RRA> is implicitly created, I<rows> will be set to the I<seasonal
-period> argument of the HWPREDICT B<RRA>. Of course, the B<rrdtool>
+period> argument of the HWPREDICT B<RRA>. Of course, the B<RRDtool>
I<resize> command is available if these defaults are not sufficient and the
create wishes to avoid explicit creations of the other specialized function
B<RRAs>.
I<seasonal period> specifies the number of primary data points in a seasonal
cycle. If SEASONAL and DEVSEASONAL are implicitly created, this argument for
those B<RRAs> is set automatically to the value specified by HWPREDICT. If
-they are explicity created, the creator should verify that all three
+they are explicitly created, the creator should verify that all three
I<seasonal period> arguments agree.
-I<alpha> is the adaptation parameter of the intercept (or baseline)
-coefficient in the Holt-Winters Forecasting algorithm. See L<rrdtool> for a
+I<alpha> is the adaption parameter of the intercept (or baseline)
+coefficient in the Holt-Winters forecasting algorithm. See L<rrdtool> for a
description of this algorithm. I<alpha> must lie between 0 and 1. A value
closer to 1 means that more recent observations carry greater weight in
predicting the baseline component of the forecast. A value closer to 0 mean
component.
I<beta> is the adaption parameter of the slope (or linear trend) coefficient
-in the Holt-Winters Forecating algorihtm. I<beta> must lie between 0 and 1
+in the Holt-Winters forecasting algorithm. I<beta> must lie between 0 and 1
and plays the same role as I<alpha> with respect to the predicted linear
trend.
I<gamma> is the adaption parameter of the seasonal coefficients in the
-Holt-Winters Forecasting algorithm (HWPREDICT) or the adaption parameter in
+Holt-Winters forecasting algorithm (HWPREDICT) or the adaption parameter in
the exponential smoothing update of the seasonal deviations. It must lie
between 0 and 1. If the SEASONAL and DEVSEASONAL B<RRAs> are created
implicitly, they will both have the same value for I<gamma>: the value
specified for the HWPREDICT I<alpha> argument. Note that because there is
one seasonal coefficient (or deviation) for each time point during the
-seasonal cycle, the adaption rate is much slower than the baseline. Each
+seasonal cycle, the adaptation rate is much slower than the baseline. Each
seasonal coefficient is only updated (or adapts) when the observed value
occurs at the offset in the seasonal cycle corresponding to that
coefficient.
-If SEASONAL and DEVSEASONAL B<RRAs> are created explicity, I<gamma> need not
+If SEASONAL and DEVSEASONAL B<RRAs> are created explicitly, I<gamma> need not
be the same for both. Note that I<gamma> can also be changed via the
-B<rrdtool> I<tune> command.
+B<RRDtool> I<tune> command.
-I<rra num> provides the links between related B<RRAs>. If HWPREDICT is
+I<rra-num> provides the links between related B<RRAs>. If HWPREDICT is
specified alone and the other B<RRAs> created implicitly, then there is no
need to worry about this argument. If B<RRAs> are created explicitly, then
pay careful attention to this argument. For each B<RRA> which includes this
argument, there is a dependency between that B<RRA> and another B<RRA>. The
-I<rra num> argument is the 1-based index in the order of B<RRA> creation
+I<rra-num> argument is the 1-based index in the order of B<RRA> creation
(that is, the order they appear in the I<create> command). The dependent
-B<RRA> for each B<RRA> requiring the I<rra num> argument is listed here:
+B<RRA> for each B<RRA> requiring the I<rra-num> argument is listed here:
=over 4
=item *
-HWPREDICT I<rra num> is the index of the SEASONAL B<RRA>.
+HWPREDICT I<rra-num> is the index of the SEASONAL B<RRA>.
=item *
-SEASONAL I<rra num> is the index of the HWPREDICT B<RRA>.
+SEASONAL I<rra-num> is the index of the HWPREDICT B<RRA>.
=item *
-DEVPREDICT I<rra num> is the index of the DEVSEASONAL B<RRA>.
+DEVPREDICT I<rra-num> is the index of the DEVSEASONAL B<RRA>.
=item *
-DEVSEASONAL I<rra num> is the index of the HWPREDICT B<RRA>.
+DEVSEASONAL I<rra-num> is the index of the HWPREDICT B<RRA>.
=item *
-FAILURES I<rra num> is the index of the DEVSEASONAL B<RRA>.
+FAILURES I<rra-num> is the index of the DEVSEASONAL B<RRA>.
=back
I<window length> is the number of time points in the window. Specify an
integer greater than or equal to the threshold and less than or equal to 28.
The time interval this window represents depends on the interval between
-primary data points. If the FAILURES B<RRA> is implicity created, the
+primary data points. If the FAILURES B<RRA> is implicitly created, the
default value is 9.
=head1 The HEARTBEAT and the STEP
-Here is an explanation by Don Baarda on the inner workings of rrdtool.
+Here is an explanation by Don Baarda on the inner workings of RRDtool.
It may help you to sort out why all this *UNKNOWN* data is popping
up in your databases:
-RRD gets fed samples at arbitrary times. From these it builds Primary
+RRDtool gets fed samples at arbitrary times. From these it builds Primary
Data Points (PDPs) at exact times every "step" interval. The PDPs are
then accumulated into RRAs.
require multiple samples per PDP, and if you don't get them mark the
PDP unknown. A long heartbeat can span multiple "steps", which means
it is acceptable to have multiple PDPs calculated from a single
-sample. An extreme example of this might be a "step" of 5mins and a
+sample. An extreme example of this might be a "step" of 5 minutes and a
"heartbeat" of one day, in which case a single sample every day will
result in all the PDPs for that entire day period being set to the
same average rate. I<-- Don Baarda E<lt>don.baarda@baesystems.comE<gt>>
=item Temperature
Normally you have some type of meter you can read to get the temperature.
-The temperature is not realy connected with a time. The only connection is
+The temperature is not really connected with a time. The only connection is
that the temperature reading happened at a certain time. You can use the
-B<GAUGE> data source type for this. RRRtool will the record your reading
+B<GAUGE> data source type for this. RRDtool will the record your reading
together with the time.
=item Mail Messages
-Assume you have a methode to count the number of messages transported by
+Assume you have a method to count the number of messages transported by
your mailserver in a certain amount of time, this give you data like '5
messages in the last 65 seconds'. If you look at the count of 5 like and
-B<ABSOLUTE> datatype you can simply update the rrd with the number 5 and the
+B<ABSOLUTE> data type you can simply update the RRD with the number 5 and the
end time of your monitoring period. RRDtool will then record the number of
messages per second. If at some later stage you want to know the number of
messages transported in a day, you can get the average messages per second
temperatures supplied for 100 hours (1200 * 300 seconds = 100
hours). The second RRA stores the minimum temperature recorded over
every hour (12 * 300 seconds = 1 hour), for 100 days (2400 hours). The
-third and the fourth RRA's do the same with the for the maximum and
+third and the fourth RRA's do the same for the maximum and
average temperature, respectively.
=head1 EXAMPLE 2
RRA:HWPREDICT:1440:0.1:0.0035:288>
This example is a monitor of a router interface. The first B<RRA> tracks the
-traffic flow in octects; the second B<RRA> generates the specialized
-functions B<RRAs> for aberrant behavior detection. Note that the I<rra num>
+traffic flow in octets; the second B<RRA> generates the specialized
+functions B<RRAs> for aberrant behavior detection. Note that the I<rra-num>
argument of HWPREDICT is missing, so the other B<RRAs> will be implicitly be
created with default parameter values. In this example, the forecasting
algorithm baseline adapts quickly; in fact the most recent one hour of
exponential smoothing formula described in a forthcoming LISA 2000 paper.
The seasonal cycle is one day (288 data points at 300 second intervals), and
-the seasonal adaption paramter will be set to 0.1. The RRD file will store 5
+the seasonal adaption parameter will be set to 0.1. The RRD file will store 5
days (1440 data points) of forecasts and deviation predictions before wrap
around. The file will store 1 day (a seasonal cycle) of 0-1 indicators in
the FAILURES B<RRA>.
Of course, explicit creation need not replicate implicit create, a number of arguments
could be changed.
+=head1 EXAMPLE 3
+
+C<rrdtool create proxy.rrd --step 300
+DS:TotalRequests:DERIVE:1800:0:U
+DS:AccumDuration:DERIVE:1800:0:U
+DS:AvgReqDuration:COMPUTE:AccumDuration,TotalRequests,0,EQ,1,TotalRequests,IF,/
+RRA:AVERAGE:0.5:1:2016>
+
+This example is monitoring the average request duration during each 300 sec
+interval for requests processed by a web proxy during the interval.
+In this case, the proxy exposes two counters, the number of requests
+processed since boot and the total cumulative duration of all processed
+requests. Clearly these counters both have some rollover point, but using the
+DERIVE data source also handles the reset that occurs when the web proxy is
+stopped and restarted.
+
+In the B<RRD>, the first data source stores the requests per second rate
+during the interval. The second data source stores the total duration of all
+requests processed during the interval divided by 300. The COMPUTE data source
+divides each PDP of the AccumDuration by the corresponding PDP of
+TotalRequests and stores the average request duration. The remainder of the
+RPN expression handles the divide by zero case.
+
=head1 AUTHOR
Tobias Oetiker E<lt>oetiker@ee.ethz.chE<gt>
projects / rrdtool.git / blobdiff