Tribblix: manual page: rrdcreate.1

RRDCREATE(1) rrdtool RRDCREATE(1)

NAME

rrdcreate - Set up a new Round Robin Database

SYNOPSIS

DESCRIPTION

The create function of RRDtool lets you set up new Round Robin
Database (RRD) files. The file is created at its final, full size
and filled with *UNKNOWN* data, unless one or more source RRD files
have been specified and they hold suitable data to "pre-fill" the new
RRD file.

filename
The name of the RRD you want to create. RRD files should end with the
extension .rrd. However, RRDtool will accept any filename.

--start|-b start time (default: now - 10s)
Specifies the time in seconds since 1970-01-01 UTC when the first
value should be added to the RRD. RRDtool will not accept any data
timed before or at the time specified.

See also "AT-STYLE TIME SPECIFICATION" in rrdfetch for other ways to
specify time.

If one or more source files is used to pre-fill the new RRD, the
--start option may be omitted. In that case, the latest update time
among all source files will be used as the last update time of the
new RRD file, effectively setting the start time.

--step|-s step (default: 300 seconds)
Specifies the base interval in seconds with which data will be fed
into the RRD. A scaling factor may be present as a suffix to the
integer; see "STEP, HEARTBEAT, and Rows As Durations".

--no-overwrite|-O
Do not clobber an existing file of the same name.

--daemon|-d address
Address of the rrdcached daemon. For a list of accepted formats, see
the -l option in the rrdcached manual.

rrdtool create --daemon unix:/var/run/rrdcached.sock /var/lib/rrd/foo.rrd I<other options>

[--template|-t template-file]
Specifies a template RRD file to take step, DS and RRA definitions
from. This allows one to base the structure of a new file on some
existing file. The data of the template file is NOT used for pre-
filling, but it is possible to specify the same file as a source file
(see below).

Additional DS and RRA definitions are permitted, and will be added to
those taken from the template.

--source|-r source-file
One or more source RRD files may be named on the command line. Data
from these source files will be used to prefill the created RRD file.
The output file and one source file may refer to the same file name.
This will effectively replace the source file with the new RRD file.
While there is the danger to loose the source file because it gets
replaced, there is no danger that the source and the new file may be
"garbled" together at any point in time, because the new file will
always be created as a temporary file first and will only be moved to
its final destination once it has been written in its entirety.

Prefilling is done by matching up DS names, RRAs and consolidation
functions and choosing the best available data resolution when doing
so. Prefilling may not be mathematically correct in all cases (e.g.
if resolutions have to change due to changed stepping of the target
RRD and old and new resolutions do not match up with old/new bin
boundaries in RRAs).

In other words: A best effort is made to preserve data during
prefilling. Also, pre-filling of RRAs may only be possible for
certain kinds of DS types. Prefilling may also have strange effects
on Holt-Winters forecasting RRAs. In other words: there is no
guarantee for data-correctness.

When "pre-filling" a RRD file, the structure of the new file must be
specified as usual using DS and RRA specifications as outlined below.
Data will be taken from source files based on DS names and types and
in the order the source files are specified in. Data sources with the
same name from different source files will be combined to form a new
data source. Generally, for any point in time the new RRD file will
cover after its creation, data from only one source file will have
been used for pre-filling. However, data from multiple sources may be
combined if it refers to different times or an earlier named source
file holds unknown data for a time where a later one holds known
data.

If this automatic data selection is not desired, the DS syntax allows
one to specify a mapping of target and source data sources for
prefilling. This syntax allows one to rename data sources and to
restrict prefilling for a DS to only use data from a single source
file.

Prefilling currently only works reliably for RRAs using one of the
classic consolidation functions, that is one of: AVERAGE, MIN, MAX,
LAST. It might also currently have problems with COMPUTE data
sources.

Note that the act of prefilling during create is similar to a lot of
the operations available via the tune command, but using create
syntax.

DS:ds-name[=mapped-ds-name[[source-index]]]:DST:dst arguments
A single RRD can accept input from several data sources (DS), for
example incoming and outgoing traffic on a specific communication
line. With the DS configuration option you must define some basic
properties of each data source you want to store in the RRD.

ds-name is the name you will use to reference this particular data
source from an RRD. A ds-name must be 1 to 19 characters long in the
characters [a-zA-Z0-9_].

DST defines the Data Source Type. The remaining arguments of a data
source entry depend on the data source type. For GAUGE, COUNTER,
DERIVE, DCOUNTER, DDERIVE and ABSOLUTE the format for a data source
entry is:

DS:ds-name:{GAUGE | COUNTER | DERIVE | DCOUNTER | DDERIVE |
ABSOLUTE}:heartbeat:min:max

For COMPUTE data sources, the format is:

DS:ds-name:COMPUTE:rpn-expression

In order to decide which data source type to use, review the
definitions that follow. Also consult the section on "HOW TO MEASURE"
for further insight.

GAUGE
is for things like temperatures or number of people in a room or
the value of a RedHat share.

COUNTER
is for continuous incrementing counters like the ifInOctets
counter in a router. The 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 the 32bit or 64bit border and
acts accordingly by adding an appropriate value to the result.

DCOUNTER
the same as COUNTER, but for quantities expressed as double-
precision floating point number. Could be used to track
quantities that increment by non-integer numbers, i.e. number of
seconds that some routine has taken to run, total weight
processed by some technology equipment etc. The only substantial
difference is that DCOUNTER can either be upward counting or
downward counting, but not both at the same time. The current
direction is detected automatically on the second non-undefined
counter update and any further change in the direction is
considered a reset. The new direction is determined and locked
in by the second update after reset and its difference to the
value at reset.

DERIVE
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 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.

DDERIVE
the same as DERIVE, but for quantities expressed as double-
precision floating point number.

NOTE on COUNTER vs DERIVE

by Don Baarda <don.baarda@baesystems.com>

If you cannot tolerate ever mistaking the occasional counter
reset for a legitimate counter wrap, and would prefer "Unknowns"
for all legitimate counter wraps and resets, always use DERIVE
with min=0. Otherwise, using COUNTER with a suitable max will
return correct values for all legitimate counter wraps, mark some
counter resets as "Unknown", but can mistake some counter resets
for a legitimate counter wrap.

For a 5 minute step and 32-bit counter, the probability of
mistaking a counter reset for a legitimate wrap is arguably about
0.8% per 1Mbps of maximum bandwidth. Note that this equates to
80% for 100Mbps interfaces, so for high bandwidth interfaces and
a 32bit counter, DERIVE with min=0 is 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.

ABSOLUTE
is for counters which get reset upon reading. This is used for
fast counters which tend to overflow. So instead of reading them
normally you reset them after every read to make sure you have a
maximum time available before the next overflow. Another usage is
for things you count like number of messages since the last
update.

COMPUTE
is for storing the result of a formula applied to other data
sources in the 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, such data sets are referred to as "virtual" or
"computed" columns.

heartbeat defines the maximum number of seconds that may pass between
two updates of this data source before the value of the data source
is assumed to be *UNKNOWN*.

min and max define the expected range values for data supplied by a
data source. If min and/or max are specified any value outside the
defined range will be regarded as *UNKNOWN*. If you do not know or
care about min and max, set them to U for unknown. Note that min and
max always refer to the processed values of the DS. For a
traffic-COUNTER type DS this would be the maximum and minimum data-
rate expected from the device.

If information on minimal/maximal expected values is available,
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.

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 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 CDEFs must
refer only to DEFs and CDEFs previously defined in the same graph
command.

When pre-filling the new RRD file using one or more source RRDs, the
DS specification may hold an optional mapping after the DS name. This
takes the form of an equal sign followed by a mapped-to DS name and
an optional source index enclosed in square brackets.

For example, the DS

DS:a=b[2]:GAUGE:120:0:U

specifies that the DS named a should be pre-filled from the DS named
b in the second listed source file (source indices are 1-based).

RRA:CF:cf arguments
The purpose of an RRD is to store data in the round robin archives
(RRA). An archive consists of a number of data values or statistics
for each of the defined data-sources (DS) and is defined with an RRA
line.

When data is entered into an RRD, it is first fit into time slots of
the length defined with the -s option, thus becoming a primary data
point.

The data is also processed with the consolidation function (CF) of
the archive. There are several consolidation functions that
consolidate primary data points via an aggregate function: AVERAGE,
MIN, MAX, LAST.

AVERAGE
the average of the data points is stored.

MIN the smallest of the data points is stored.

MAX the largest of the data points is stored.

LAST
the last data points is used.

Note that data aggregation inevitably leads to loss of precision and
information. The trick is to pick the aggregate function such that
the interesting properties of your data is kept across the
aggregation process.

The format of RRA line for these consolidation functions is:

RRA:{AVERAGE | MIN | MAX | LAST}:xff:steps:rows

xff The xfiles factor defines what part of a consolidation interval
may be made up from *UNKNOWN* data while the consolidated value is
still regarded as known. It is given as the ratio of allowed
*UNKNOWN* PDPs to the number of PDPs in the interval. Thus, it ranges
from 0 to 1 (exclusive).

steps defines how many of these primary data points are used to build
a consolidated data point which then goes into the archive. See also
"STEP, HEARTBEAT, and Rows As Durations".

rows defines how many generations of data values are kept in an RRA.
Obviously, this has to be greater than zero. See also "STEP,
HEARTBEAT, and Rows As Durations".

Aberrant Behavior Detection with Holt-Winters Forecasting
In addition to the aggregate functions, there are a set of
specialized functions that enable RRDtool to provide data smoothing
(via the Holt-Winters forecasting algorithm), confidence bands, and
the flagging aberrant behavior in the data source time series:

+o RRA:HWPREDICT:rows:alpha:beta:seasonal period[:rra-num]

+o RRA:MHWPREDICT:rows:alpha:beta:seasonal period[:rra-num]

+o RRA:SEASONAL:seasonal period:gamma:rra-
num[:smoothing-window=fraction]

+o RRA:DEVSEASONAL:seasonal period:gamma:rra-
num[:smoothing-window=fraction]

+o RRA:DEVPREDICT:rows:rra-num

+o RRA:FAILURES:rows:threshold:window length:rra-num

These RRAs differ from the true consolidation functions in several
ways. First, each of the RRAs is updated once for every primary data
point. Second, these RRAs are interdependent. To generate real-time
confidence bounds, a matched set of SEASONAL, DEVSEASONAL,
DEVPREDICT, and either HWPREDICT or MHWPREDICT must exist. Generating
smoothed values of the primary data points requires a SEASONAL RRA
and either an HWPREDICT or MHWPREDICT RRA. Aberrant behavior
detection requires FAILURES, DEVSEASONAL, SEASONAL, and either
HWPREDICT or MHWPREDICT.

The predicted, or smoothed, values are stored in the HWPREDICT or
MHWPREDICT RRA. HWPREDICT and MHWPREDICT 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. HWPREDICT adds its seasonal coefficient to the
baseline to form a prediction, whereas MHWPREDICT 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; HWPREDICT will predict the seasonality to
stay constant as the baseline changes, but MHWPREDICT 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 HWPREDICT, but
MHWPREDICT may be substituted in its place.

The predicted deviations are stored in DEVPREDICT (think a standard
deviation which can be scaled to yield a confidence band). The
FAILURES RRA 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 RRAs to graph
confidence bounds and failures appears in rrdgraph.

The SEASONAL and DEVSEASONAL RRAs store the seasonal coefficients for
the 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 will have 288 rows.

In order to simplify the creation for the novice user, in addition to
supporting explicit creation of the HWPREDICT, SEASONAL, DEVPREDICT,
DEVSEASONAL, and FAILURES RRAs, the RRDtool create command supports
implicit creation of the other four when HWPREDICT is specified alone
and the final argument rra-num is omitted.

rows specifies the length of the 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, rows should be
larger than the seasonal period. If the DEVPREDICT RRA is implicitly
created, the default number of rows is the same as the HWPREDICT rows
argument. If the FAILURES RRA is implicitly created, rows will be set
to the seasonal period argument of the HWPREDICT RRA. Of course, the
RRDtool resize command is available if these defaults are not
sufficient and the creator wishes to avoid explicit creations of the
other specialized function RRAs.

seasonal period specifies the number of primary data points in a
seasonal cycle. If SEASONAL and DEVSEASONAL are implicitly created,
this argument for those RRAs is set automatically to the value
specified by HWPREDICT. If they are explicitly created, the creator
should verify that all three seasonal period arguments agree.

alpha is the adaption parameter of the intercept (or baseline)
coefficient in the Holt-Winters forecasting algorithm. See rrdtool
for a description of this algorithm. 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 means that past history carries greater weight in
predicting the baseline component.

beta is the adaption parameter of the slope (or linear trend)
coefficient in the Holt-Winters forecasting algorithm. beta must lie
between 0 and 1 and plays the same role as alpha with respect to the
predicted linear trend.

gamma is the adaption parameter of the seasonal coefficients in the
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 RRAs are created implicitly, they will both have the same
value for gamma: the value specified for the HWPREDICT alpha
argument. Note that because there is one seasonal coefficient (or
deviation) for each time point during the 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 RRAs are created explicitly, gamma need
not be the same for both. Note that gamma can also be changed via the
RRDtool tune command.

smoothing-window specifies the fraction of a season that should be
averaged around each point. By default, the value of smoothing-window
is 0.05, which means each value in SEASONAL and DEVSEASONAL will be
occasionally replaced by averaging it with its (seasonal period*0.05)
nearest neighbors. Setting smoothing-window to zero will disable the
running-average smoother altogether.

rra-num provides the links between related RRAs. If HWPREDICT is
specified alone and the other RRAs are created implicitly, then there
is no need to worry about this argument. If RRAs are created
explicitly, then carefully pay attention to this argument. For each
RRA which includes this argument, there is a dependency between that
RRA and another RRA. The rra-num argument is the 1-based index in the
order of RRA creation (that is, the order they appear in the create
command). The dependent RRA for each RRA requiring the rra-num
argument is listed here:

+o HWPREDICT rra-num is the index of the SEASONAL RRA.

+o SEASONAL rra-num is the index of the HWPREDICT RRA.

+o DEVPREDICT rra-num is the index of the DEVSEASONAL RRA.

+o DEVSEASONAL rra-num is the index of the HWPREDICT RRA.

+o FAILURES rra-num is the index of the DEVSEASONAL RRA.

threshold is the minimum number of violations (observed values
outside the confidence bounds) within a window that constitutes a
failure. If the FAILURES RRA is implicitly created, the default value
is 7.

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 RRA is
implicitly created, the default value is 9.

STEP, HEARTBEAT, and Rows As Durations
Traditionally RRDtool specified PDP intervals in seconds, and most
other values as either seconds or PDP counts. This made the
specification for databases rather opaque; for example

rrdtool create power.rrd \
--start now-2h --step 1 \
DS:watts:GAUGE:300:0:24000 \
RRA:AVERAGE:0.5:1:864000 \
RRA:AVERAGE:0.5:60:129600 \
RRA:AVERAGE:0.5:3600:13392 \
RRA:AVERAGE:0.5:86400:3660

creates a database of power values collected once per second, with a
five minute (300 second) heartbeat, and four RRAs: ten days of one
second, 90 days of one minute, 18 months of one hour, and ten years
of one day averages.

Step, heartbeat, and PDP counts and rows may also be specified as
durations, which are positive integers with a single-character suffix
that specifies a scaling factor. See "rrd_scaled_duration" in librrd
for scale factors of the supported suffixes: "s" (seconds), "m"
(minutes), "h" (hours), "d" (days), "w" (weeks), "M" (months), and
"y" (years).

Scaled step and heartbeat values (which are natively durations in
seconds) are used directly, while consolidation function row
arguments are divided by their step to produce the number of rows.

With this feature the same specification as above can be written as:

rrdtool create power.rrd \
--start now-2h --step 1s \
DS:watts:GAUGE:5m:0:24000 \
RRA:AVERAGE:0.5:1s:10d \
RRA:AVERAGE:0.5:1m:90d \
RRA:AVERAGE:0.5:1h:18M \
RRA:AVERAGE:0.5:1d:10y

The HEARTBEAT and the STEP
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:

RRDtool gets fed samples/updates at arbitrary times. From these it
builds Primary Data Points (PDPs) on every "step" interval. The PDPs
are then accumulated into the RRAs.

The "heartbeat" defines the maximum acceptable interval between
samples/updates. If the interval between samples is less than
"heartbeat", then an average rate is calculated and applied for that
interval. If the interval between samples is longer than "heartbeat",
then that entire interval is considered "unknown". Note that there
are other things that can make a sample interval "unknown", such as
the rate exceeding limits, or a sample that was explicitly marked as
unknown.

The known rates during a PDP's "step" interval are used to calculate
an average rate for that PDP. If the total "unknown" time accounts
for more than half the "step", the entire PDP is marked as "unknown".
This means that a mixture of known and "unknown" sample times in a
single PDP "step" may or may not add up to enough "known" time to
warrant a known PDP.

The "heartbeat" can be short (unusual) or long (typical) relative to
the "step" interval between PDPs. A short "heartbeat" means you
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 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. -- Don Baarda <don.baarda@baesystems.com>

time|
axis|
begin__|00|
|01|
u|02|----* sample1, restart "hb"-timer
u|03| /
u|04| /
u|05| /
u|06|/ "hbt" expired
u|07|
|08|----* sample2, restart "hb"
|09| /
|10| /
u|11|----* sample3, restart "hb"
u|12| /
u|13| /
step1_u|14| /
u|15|/ "swt" expired
u|16|
|17|----* sample4, restart "hb", create "pdp" for step1 =
|18| / = unknown due to 10 "u" labeled secs > 0.5 * step
|19| /
|20| /
|21|----* sample5, restart "hb"
|22| /
|23| /
|24|----* sample6, restart "hb"
|25| /
|26| /
|27|----* sample7, restart "hb"
step2__|28| /
|22| /
|23|----* sample8, restart "hb", create "pdp" for step1, create "cdp"
|24| /
|25| /

graphics by vladimir.lavrov@desy.de.

HOW TO MEASURE

Here are a few hints on how to measure:

Temperature
Usually you have some type of meter you can read to get the
temperature. 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 GAUGE data source
type for this. RRDtool will then record your reading together
with the time.

Mail Messages
Assume you have a method to count the number of messages
transported by your mail server in a certain amount of time,
giving you data like '5 messages in the last 65 seconds'. If you
look at the count of 5 like an 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 from RRDtool for the day in question and
multiply this number with the number of seconds in a day. Because
all math is run with Doubles, the precision should be acceptable.

It's always a Rate
RRDtool stores rates in amount/second for COUNTER, DERIVE,
DCOUNTER, DDERIVE and ABSOLUTE data. When you plot the data, you
will get on the y axis amount/second which you might be tempted
to convert to an absolute amount by multiplying by the delta-time
between the points. RRDtool plots continuous data, and as such is
not appropriate for plotting absolute amounts as for example
"total bytes" sent and received in a router. What you probably
want is plot rates that you can scale to bytes/hour, for example,
or plot absolute amounts with another tool that draws bar-plots,
where the delta-time is clear on the plot for each point (such
that when you read the graph you see for example GB on the y
axis, days on the x axis and one bar for each day).

EXAMPLE

rrdtool create temperature.rrd --step 300 \
DS:temp:GAUGE:600:-273:5000 \
RRA:AVERAGE:0.5:1:1200 \
RRA:MIN:0.5:12:2400 \
RRA:MAX:0.5:12:2400 \
RRA:AVERAGE:0.5:12:2400

This sets up an RRD called temperature.rrd which accepts one
temperature value every 300 seconds. If no new data is supplied for
more than 600 seconds, the temperature becomes *UNKNOWN*. The
minimum acceptable value is -273 and the maximum is 5'000.

A few archive areas are also defined. The first stores the
temperatures supplied for 100 hours (1'200 * 300 seconds = 100
hours). The second RRA stores the minimum temperature recorded over
every hour (12 * 300 seconds = 1 hour), for 100 days (2'400 hours).
The third and the fourth RRA's do the same for the maximum and
average temperature, respectively.

EXAMPLE 2
rrdtool create monitor.rrd --step 300 \
DS:ifOutOctets:COUNTER:1800:0:4294967295 \
RRA:AVERAGE:0.5:1:2016 \
RRA:HWPREDICT:1440:0.1:0.0035:288

This example is a monitor of a router interface. The first RRA tracks
the traffic flow in octets; the second RRA generates the specialized
functions RRAs for aberrant behavior detection. Note that the rra-num
argument of HWPREDICT is missing, so the other RRAs will implicitly
be created with default parameter values. In this example, the
forecasting algorithm baseline adapts quickly; in fact the most
recent one hour of observations (each at 5 minute intervals) accounts
for 75% of the baseline prediction. The linear trend forecast adapts
much more slowly. Observations made during the last day (at 288
observations per day) account for only 65% of the predicted linear
trend. Note: these computations rely on an exponential smoothing
formula described in the LISA 2000 paper.

The seasonal cycle is one day (288 data points at 300 second
intervals), and the seasonal adaption parameter will be set to 0.1.
The RRD file will store 5 days (1'440 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 RRA.

The same RRD file and RRAs are created with the following command,
which explicitly creates all specialized function RRAs using "STEP,
HEARTBEAT, and Rows As Durations".

rrdtool create monitor.rrd --step 5m \
DS:ifOutOctets:COUNTER:30m:0:4294967295 \
RRA:AVERAGE:0.5:1:2016 \
RRA:HWPREDICT:5d:0.1:0.0035:1d:3 \
RRA:SEASONAL:1d:0.1:2 \
RRA:DEVSEASONAL:1d:0.1:2 \
RRA:DEVPREDICT:5d:5 \
RRA:FAILURES:1d:7:9:5

Of course, explicit creation need not replicate implicit create, a
number of arguments could be changed.

EXAMPLE 3
rrdtool create proxy.rrd --step 300 \
DS:Requests:DERIVE:1800:0:U \
DS:Duration:DERIVE:1800:0:U \
DS:AvgReqDur:COMPUTE:Duration,Requests,0,EQ,1,Requests,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 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.

SECURITY

Note that new rrd files will have the permission 0644 regardless of
your umask setting. If a file with the same name previously exists,
its permission settings will be copied to the new file.

AUTHORS

Tobias Oetiker <tobi@oetiker.ch>, Peter Stamfest <peter@stamfest.at>

1.8.0 2022-03-14 RRDCREATE(1)