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diff --git a/doc/rrdcreate.1 b/doc/rrdcreate.1
index f32da3624c6964bae732a7ab398895f2ab4b770c..8ceba9b227dee4ce38b3f938090b527f8fe2c86f 100644 (file)
--- a/doc/rrdcreate.1
+++ b/doc/rrdcreate.1
.\" ========================================================================
.\"
.IX Title "RRDCREATE 1"
-.TH RRDCREATE 1 "2008-02-17" "1.2.27" "rrdtool"
+.TH RRDCREATE 1 "2008-05-12" "1.3rc4" "rrdtool"
.SH "NAME"
rrdcreate \- Set up a new Round Robin Database
.SH "SYNOPSIS"
The create function of RRDtool lets you set up new Round Robin
Database (\fB\s-1RRD\s0\fR) files. The file is created at its final, full size
and filled with \fI*UNKNOWN*\fR data.
-.IP "\fIfilename\fR" 4
+.IP "\fIfilename\fR" 8
.IX Item "filename"
The name of the \fB\s-1RRD\s0\fR you want to create. \fB\s-1RRD\s0\fR files should end
with the extension \fI.rrd\fR. However, \fBRRDtool\fR will accept any
filename.
-.IP "\fB\-\-start\fR|\fB\-b\fR \fIstart time\fR (default: now \- 10s)" 4
+.IP "\fB\-\-start\fR|\fB\-b\fR \fIstart time\fR (default: now \- 10s)" 8
.IX Item "--start|-b start time (default: now - 10s)"
Specifies the time in seconds since 1970\-01\-01 \s-1UTC\s0 when the first
value should be added to the \fB\s-1RRD\s0\fR. \fBRRDtool\fR will not accept
.Sp
See also AT-STYLE \s-1TIME\s0 \s-1SPECIFICATION\s0 section in the
\&\fIrrdfetch\fR documentation for other ways to specify time.
-.IP "\fB\-\-step\fR|\fB\-s\fR \fIstep\fR (default: 300 seconds)" 4
+.IP "\fB\-\-step\fR|\fB\-s\fR \fIstep\fR (default: 300 seconds)" 8
.IX Item "--step|-s step (default: 300 seconds)"
Specifies the base interval in seconds with which data will be fed
into the \fB\s-1RRD\s0\fR.
-.IP "\fB\s-1DS:\s0\fR\fIds-name\fR\fB:\fR\fI\s-1DST\s0\fR\fB:\fR\fIdst arguments\fR" 4
+.IP "\fB\s-1DS:\s0\fR\fIds-name\fR\fB:\fR\fI\s-1DST\s0\fR\fB:\fR\fIdst arguments\fR" 8
.IX Item "DS:ds-name:DST:dst arguments"
A single \fB\s-1RRD\s0\fR can accept input from several data sources (\fB\s-1DS\s0\fR),
for example incoming and outgoing traffic on a specific communication
In order to decide which data source type to use, review the
definitions that follow. Also consult the section on \*(L"\s-1HOW\s0 \s-1TO\s0 \s-1MEASURE\s0\*(R"
for further insight.
-.RS 4
+.RS 8
.IP "\fB\s-1GAUGE\s0\fR" 4
.IX Item "GAUGE"
is for things like temperatures or number of people in a room or the
room. Internally, derive works exactly like \s-1COUNTER\s0 but without
overflow checks. So if your counter does not reset at 32 or 64 bit you
might want to use \s-1DERIVE\s0 and combine it with a \s-1MIN\s0 value of 0.
-.Sp
-\&\s-1NOTE\s0 on \s-1COUNTER\s0 vs \s-1DERIVE\s0
-.Sp
+.RS 4
+.IP "\s-1NOTE\s0 on \s-1COUNTER\s0 vs \s-1DERIVE\s0" 4
+.IX Item "NOTE on COUNTER vs DERIVE"
by Don Baarda <don.baarda@baesystems.com>
.Sp
If you cannot tolerate ever mistaking the occasional counter reset for a
probably preferable. If you are using a 64bit counter, just about any max
setting will eliminate the possibility of mistaking a reset for a counter
wrap.
+.RE
+.RS 4
+.RE
.IP "\fB\s-1ABSOLUTE\s0\fR" 4
.IX Item "ABSOLUTE"
is for counters which get reset upon reading. This is used for fast counters
to generate PDPs). In database software, such data sets are referred
to as \*(L"virtual\*(R" or \*(L"computed\*(R" columns.
.RE
-.RS 4
+.RS 8
.Sp
\&\fIheartbeat\fR defines the maximum number of seconds that may pass
between two updates of this data source before the value of the
similar to the restriction that \fB\s-1CDEF\s0\fRs must refer only to \fB\s-1DEF\s0\fRs
and \fB\s-1CDEF\s0\fRs previously defined in the same graph command.
.RE
-.IP "\fB\s-1RRA:\s0\fR\fI\s-1CF\s0\fR\fB:\fR\fIcf arguments\fR" 4
+.IP "\fB\s-1RRA:\s0\fR\fI\s-1CF\s0\fR\fB:\fR\fIcf arguments\fR" 8
.IX Item "RRA:CF:cf arguments"
The purpose of an \fB\s-1RRD\s0\fR is to store data in the round robin archives
(\fB\s-1RRA\s0\fR). An archive consists of a number of data values or statistics for
The data is also processed with the consolidation function (\fI\s-1CF\s0\fR) of
the archive. There are several consolidation functions that
consolidate primary data points via an aggregate function: \fB\s-1AVERAGE\s0\fR,
-\&\fB\s-1MIN\s0\fR, \fB\s-1MAX\s0\fR, \fB\s-1LAST\s0\fR. The format of \fB\s-1RRA\s0\fR line for these
+\&\fB\s-1MIN\s0\fR, \fB\s-1MAX\s0\fR, \fB\s-1LAST\s0\fR.
+.RS 8
+.IP "\s-1AVERAGE\s0" 4
+.IX Item "AVERAGE"
+the average of the data points is stored.
+.IP "\s-1MIN\s0" 4
+.IX Item "MIN"
+the smallest of the data points is stored.
+.IP "\s-1MAX\s0" 4
+.IX Item "MAX"
+the largest of the data points is stored.
+.IP "\s-1LAST\s0" 4
+.IX Item "LAST"
+the last data points is used.
+.RE
+.RS 8
+.Sp
+Note that data aggregation inevitably leads to loss of precision and
+information. The trick is to pick the aggregate function such that the
+\&\fIinteresting\fR properties of your data is kept across the aggregation
+process.
+.Sp
+The format of \fB\s-1RRA\s0\fR line for these
consolidation functions is:
.Sp
\&\fB\s-1RRA:\s0\fR\fI\s-1AVERAGE\s0 | \s-1MIN\s0 | \s-1MAX\s0 | \s-1LAST\s0\fR\fB:\fR\fIxff\fR\fB:\fR\fIsteps\fR\fB:\fR\fIrows\fR
a \fIconsolidated data point\fR which then goes into the archive.
.Sp
\&\fIrows\fR defines how many generations of data values are kept in an \fB\s-1RRA\s0\fR.
+.RE
.SH "Aberrant Behavior Detection with Holt-Winters Forecasting"
.IX Header "Aberrant Behavior Detection with Holt-Winters Forecasting"
In addition to the aggregate functions, there are a set of specialized
.IP "\(bu" 4
\&\fB\s-1RRA:\s0\fR\fI\s-1HWPREDICT\s0\fR\fB:\fR\fIrows\fR\fB:\fR\fIalpha\fR\fB:\fR\fIbeta\fR\fB:\fR\fIseasonal period\fR[\fB:\fR\fIrra-num\fR]
.IP "\(bu" 4
-\&\fB\s-1RRA:\s0\fR\fI\s-1SEASONAL\s0\fR\fB:\fR\fIseasonal period\fR\fB:\fR\fIgamma\fR\fB:\fR\fIrra-num\fR
+\&\fB\s-1RRA:\s0\fR\fI\s-1MHWPREDICT\s0\fR\fB:\fR\fIrows\fR\fB:\fR\fIalpha\fR\fB:\fR\fIbeta\fR\fB:\fR\fIseasonal period\fR[\fB:\fR\fIrra-num\fR]
.IP "\(bu" 4
-\&\fB\s-1RRA:\s0\fR\fI\s-1DEVSEASONAL\s0\fR\fB:\fR\fIseasonal period\fR\fB:\fR\fIgamma\fR\fB:\fR\fIrra-num\fR
+\&\fB\s-1RRA:\s0\fR\fI\s-1SEASONAL\s0\fR\fB:\fR\fIseasonal period\fR\fB:\fR\fIgamma\fR\fB:\fR\fIrra-num\fR[\fB:smoothing\-window=\fR\fIfraction\fR]
+.IP "\(bu" 4
+\&\fB\s-1RRA:\s0\fR\fI\s-1DEVSEASONAL\s0\fR\fB:\fR\fIseasonal period\fR\fB:\fR\fIgamma\fR\fB:\fR\fIrra-num\fR[\fB:smoothing\-window=\fR\fIfraction\fR]
.IP "\(bu" 4
\&\fB\s-1RRA:\s0\fR\fI\s-1DEVPREDICT\s0\fR\fB:\fR\fIrows\fR\fB:\fR\fIrra-num\fR
.IP "\(bu" 4
These \fBRRAs\fR differ from the true consolidation functions in several ways.
First, each of the \fB\s-1RRA\s0\fRs is updated once for every primary data point.
Second, these \fBRRAs\fR are interdependent. To generate real-time confidence
-bounds, a matched set of \s-1HWPREDICT\s0, \s-1SEASONAL\s0, \s-1DEVSEASONAL\s0, and
-\&\s-1DEVPREDICT\s0 must exist. Generating smoothed values of the primary data points
-requires both a \s-1HWPREDICT\s0 \fB\s-1RRA\s0\fR and \s-1SEASONAL\s0 \fB\s-1RRA\s0\fR. Aberrant behavior
-detection requires \s-1FAILURES\s0, \s-1HWPREDICT\s0, \s-1DEVSEASONAL\s0, and \s-1SEASONAL\s0.
-.PP
-The actual predicted, or smoothed, values are stored in the \s-1HWPREDICT\s0
-\&\fB\s-1RRA\s0\fR. The predicted deviations are stored in \s-1DEVPREDICT\s0 (think a standard
-deviation which can be scaled to yield a confidence band). The \s-1FAILURES\s0
-\&\fB\s-1RRA\s0\fR stores binary indicators. A 1 marks the indexed observation as
-failure; that is, the number of confidence bounds violations in the
-preceding window of observations met or exceeded a specified threshold. An
-example of using these \fBRRAs\fR to graph confidence bounds and failures
-appears in rrdgraph.
+bounds, a matched set of \s-1SEASONAL\s0, \s-1DEVSEASONAL\s0, \s-1DEVPREDICT\s0, and either
+\&\s-1HWPREDICT\s0 or \s-1MHWPREDICT\s0 must exist. Generating smoothed values of the primary
+data points requires a \s-1SEASONAL\s0 \fB\s-1RRA\s0\fR and either an \s-1HWPREDICT\s0 or \s-1MHWPREDICT\s0
+\&\fB\s-1RRA\s0\fR. Aberrant behavior detection requires \s-1FAILURES\s0, \s-1DEVSEASONAL\s0, \s-1SEASONAL\s0,
+and either \s-1HWPREDICT\s0 or \s-1MHWPREDICT\s0.
+.PP
+The predicted, or smoothed, values are stored in the \s-1HWPREDICT\s0 or \s-1MHWPREDICT\s0
+\&\fB\s-1RRA\s0\fR. \s-1HWPREDICT\s0 and \s-1MHWPREDICT\s0 are actually two variations on the
+Holt-Winters method. They are interchangeable. Both attempt to decompose data
+into three components: a baseline, a trend, and a seasonal coefficient.
+\&\s-1HWPREDICT\s0 adds its seasonal coefficient to the baseline to form a prediction, whereas
+\&\s-1MHWPREDICT\s0 multiplies its seasonal coefficient by the baseline to form a
+prediction. The difference is noticeable when the baseline changes
+significantly in the course of a season; \s-1HWPREDICT\s0 will predict the seasonality
+to stay constant as the baseline changes, but \s-1MHWPREDICT\s0 will predict the
+seasonality to grow or shrink in proportion to the baseline. The proper choice
+of method depends on the thing being modeled. For simplicity, the rest of this
+discussion will refer to \s-1HWPREDICT\s0, but \s-1MHWPREDICT\s0 may be substituted in its
+place.
+.PP
+The predicted deviations are stored in \s-1DEVPREDICT\s0 (think a standard deviation
+which can be scaled to yield a confidence band). The \s-1FAILURES\s0 \fB\s-1RRA\s0\fR stores
+binary indicators. A 1 marks the indexed observation as failure; that is, the
+number of confidence bounds violations in the preceding window of observations
+met or exceeded a specified threshold. An example of using these \fBRRAs\fR to graph
+confidence bounds and failures appears in rrdgraph.
.PP
The \s-1SEASONAL\s0 and \s-1DEVSEASONAL\s0 \fBRRAs\fR store the seasonal coefficients for the
Holt-Winters forecasting algorithm and the seasonal deviations, respectively.
@@ -391,6 +432,13 @@ If \s-1SEASONAL\s0 and \s-1DEVSEASONAL\s0 \fBRRAs\fR are created explicitly, \fI
be the same for both. Note that \fIgamma\fR can also be changed via the
\&\fBRRDtool\fR \fItune\fR command.
.PP
+\&\fIsmoothing-window\fR specifies the fraction of a season that should be
+averaged around each point. By default, the value of \fIsmoothing-window\fR is
+0.05, which means each value in \s-1SEASONAL\s0 and \s-1DEVSEASONAL\s0 will be occasionally
+replaced by averaging it with its (\fIseasonal period\fR*0.05) nearest neighbors.
+Setting \fIsmoothing-window\fR to zero will disable the running-average smoother
+altogether.
+.PP
\&\fIrra-num\fR provides the links between related \fBRRAs\fR. If \s-1HWPREDICT\s0 is
specified alone and the other \fBRRAs\fR are created implicitly, then
there is no need to worry about this argument. If \fBRRAs\fR are created
It may help you to sort out why all this *UNKNOWN* data is popping
up in your databases:
.PP
-RRDtool gets fed samples at arbitrary times. From these it builds Primary
-Data Points (PDPs) at exact times on every \*(L"step\*(R" interval. The PDPs are
-then accumulated into RRAs.
+RRDtool gets fed samples/updates at arbitrary times. From these it builds Primary
+Data Points (PDPs) on every \*(L"step\*(R" interval. The PDPs are
+then accumulated into the RRAs.
.PP
The \*(L"heartbeat\*(R" defines the maximum acceptable interval between
-samples. If the interval between samples is less than \*(L"heartbeat\*(R",
+samples/updates. If the interval between samples is less than \*(L"heartbeat\*(R",
then an average rate is calculated and applied for that interval. If
the interval between samples is longer than \*(L"heartbeat\*(R", then that
entire interval is considered \*(L"unknown\*(R". Note that there are other
things that can make a sample interval \*(L"unknown\*(R", such as the rate
-exceeding limits, or even an \*(L"unknown\*(R" input sample.
+exceeding limits, or a sample that was explicitly marked as unknown.
.PP
The known rates during a \s-1PDP\s0's \*(L"step\*(R" interval are used to calculate
-an average rate for that \s-1PDP\s0. Also, if the total \*(L"unknown\*(R" time during
-the \*(L"step\*(R" interval exceeds the \*(L"heartbeat\*(R", the entire \s-1PDP\s0 is marked
+an average rate for that \s-1PDP\s0. If the total \*(L"unknown\*(R" time accounts for
+more than \fBhalf\fR the \*(L"step\*(R", the entire \s-1PDP\s0 is marked
as \*(L"unknown\*(R". This means that a mixture of known and \*(L"unknown\*(R" sample
-times in a single \s-1PDP\s0 \*(L"step\*(R" may or may not add up to enough \*(L"unknown\*(R"
-time to exceed \*(L"heartbeat\*(R" and hence mark the whole \s-1PDP\s0 \*(L"unknown\*(R". So
-\&\*(L"heartbeat\*(R" is not only the maximum acceptable interval between
-samples, but also the maximum acceptable amount of \*(L"unknown\*(R" time per
-\&\s-1PDP\s0 (obviously this is only significant if you have \*(L"heartbeat\*(R" less
-than \*(L"step\*(R").
+times in a single \s-1PDP\s0 \*(L"step\*(R" may or may not add up to enough \*(L"known\*(R"
+time to warrent for a known \s-1PDP\s0.
.PP
The \*(L"heartbeat\*(R" can be short (unusual) or long (typical) relative to
the \*(L"step\*(R" interval between PDPs. A short \*(L"heartbeat\*(R" means you
\& u|15|/ "swt" expired
\& u|16|
\& |17|\-\-\-\-* sample4, restart "hb", create "pdp" for step1 =
-\& |18| / = unknown due to 10 "u" labled secs > "hb"
+\& |18| / = unknown due to 10 "u" labled secs > 0.5 * step
\& |19| /
\& |20| /
\& |21|\-\-\-\-* sample5, restart "hb"