RRDCREATE(1)                        RRDtool                       RRDCREATE(1)



NNAAMMEE
       rrdcreate - Set up a new Round Robin Database

SSYYNNOOPPSSIISS
       rrrrddttooooll ccrreeaattee _f_i_l_e_n_a_m_e [----ssttaarrtt|--bb _s_t_a_r_t _t_i_m_e] [----sstteepp|--ss _s_t_e_p]
       [DDSS::_d_s_-_n_a_m_e::_D_S_T::_h_e_a_r_t_b_e_a_t::_m_i_n::_m_a_x] [RRRRAA::_C_F::_x_f_f::_s_t_e_p_s::_r_o_w_s]

DDEESSCCRRIIPPTTIIOONN
       The create function of the RRDTool lets you set up new Round Robin
       Database (RRRRDD) files.  The file is created at its final, full size and
       filled with _*_U_N_K_N_O_W_N_* data.

       _f_i_l_e_n_a_m_e
               The name of the RRRRDD you want to create. RRRRDD files should end
               with the extension _._r_r_d. However, RRRRDDTTooooll will accept any file-
               name.

       ----ssttaarrtt|--bb _s_t_a_r_t _t_i_m_e (default: now - 10s)
               Specifies the time in seconds since 1970-01-01 UTC when the
               first value should be added to the RRRRDD. RRRRDDTTooooll will not accept
               any data timed before or at the time specified.

               See also AT-STYLE TIME SPECIFICATION section in the _r_r_d_f_e_t_c_h
               documentation for more ways to specify time.

       ----sstteepp|--ss _s_t_e_p (default: 300 seconds)
               Specifies the base interval in seconds with which data will be
               fed into the RRRRDD.

       DDSS::_d_s_-_n_a_m_e::_D_S_T::_h_e_a_r_t_b_e_a_t::_m_i_n::_m_a_x
               A single RRRRDD can accept input from several data sources (DDSS).
               (e.g. Incoming and Outgoing traffic on a specific communication
               line). With the DDSS configuration option you must define some
               basic properties of each data source you want to use to feed
               the RRRRDD.

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

               _D_S_T defines the Data Source Type. See the section on "How to
               Measure" below for further insight.  The Data Source Type must
               be one of the following:

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

               CCOOUUNNTTEERR
                   is for continuous incrementing counters like the InOctets
                   counter in a router. The CCOOUUNNTTEERR data source assumes that
                   the counter never decreases, except when a counter over-
                   flows.  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 hap-
                   pened at the 32bit or 64bit border and acts accordingly by
                   adding an appropriate value to the result.

               DDEERRIIVVEE
                   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.

               AABBSSOOLLUUTTEE
                   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 maximal time available before the next
                   overflow. Another usage is for things you count like number
                   of messages since the last update.

               _h_e_a_r_t_b_e_a_t 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 _*_U_N_K_N_O_W_N_*.

               _m_i_n and _m_a_x are optional entries defining the expected range of
               the data supplied by this data source. If _m_i_n and/or _m_a_x are
               defined, any value outside the defined range will be regarded
               as _*_U_N_K_N_O_W_N_*. 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-CCOOUUNNTTEERR type DS
               this would be the max and min data-rate expected from the
               device.

               _I_f _i_n_f_o_r_m_a_t_i_o_n _o_n _m_i_n_i_m_a_l_/_m_a_x_i_m_a_l _e_x_p_e_c_t_e_d _v_a_l_u_e_s _i_s _a_v_a_i_l_a_b_l_e_,
               _a_l_w_a_y_s _s_e_t _t_h_e _m_i_n _a_n_d_/_o_r _m_a_x _p_r_o_p_e_r_t_i_e_s_. _T_h_i_s _w_i_l_l _h_e_l_p _R_R_D_-
               _T_o_o_l _i_n _d_o_i_n_g _a _s_i_m_p_l_e _s_a_n_i_t_y _c_h_e_c_k _o_n _t_h_e _d_a_t_a _s_u_p_p_l_i_e_d _w_h_e_n
               _r_u_n_n_i_n_g _u_p_d_a_t_e_.

       RRRRAA::_C_F::_x_f_f::_s_t_e_p_s::_r_o_w_s
               The purpose of an RRRRDD is to store data in the round robin
               archives (RRRRAA). An archive consists of a number of data values
               from all the defined data-sources (DDSS) and is defined with an
               RRRRAA line.

               When data is entered into an RRRRDD, it is first fit into time
               slots of the length defined with the --ss option becoming a _p_r_i_-
               _m_a_r_y _d_a_t_a _p_o_i_n_t.

               The data is also consolidated with the consolidation function
               (_C_F) of the archive. The following consolidation functions are
               defined: AAVVEERRAAGGEE, MMIINN, MMAAXX, LLAASSTT.

               _x_f_f The xfiles factor defines what part of a consolidation
               interval may be made up from _*_U_N_K_N_O_W_N_* data while the consoli-
               dated value is still regarded as known.

               _s_t_e_p_s defines how many of these _p_r_i_m_a_r_y _d_a_t_a _p_o_i_n_t_s are used to
               build a _c_o_n_s_o_l_i_d_a_t_e_d _d_a_t_a _p_o_i_n_t which then goes into the
               archive.

               _r_o_w_s defines how many generations of data values are kept in an
               RRRRAA.

TThhee HHEEAARRTTBBEEAATT aanndd tthhee SSTTEEPP
       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
       Data Points (PDPs) at exact times every "step" interval. The PDPs are
       then accumulated into RRAs.

       The "heartbeat" defines the maximum acceptable interval between
       samples. 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 lim-
       its, or even an "unknown" input sample.

       The known rates during a PDP's "step" interval are used to calculate an
       average rate for that PDP. Also, if the total "unknown" time during the
       "step" interval exceeds the "heartbeat", the entire PDP is marked as
       "unknown". This means that a mixture of known and "unknown" sample time
       in a single PDP "step" may or may not add up to enough "unknown" time
       to exceed "heartbeat" and hence mark the whole PDP "unknown". So
       "heartbeat" is not only the maximum acceptable interval between sam-
       ples, but also the maximum acceptable amount of "unknown" time per PDP
       (obviously this is only significant if you have "heartbeat" less than
       "step").

       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 "heart-
       beat" 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 aver-
       age rate. _-_- _D_o_n _B_a_a_r_d_a _<_d_o_n_._b_a_a_r_d_a_@_b_a_e_s_y_s_t_e_m_s_._c_o_m_>

HHOOWW TTOO MMEEAASSUURREE
       Here are a few hints on how to measure:

       Temperature
           Normally you have some type of meter you can read to get the tem-
           perature.  The temperature is not really connected with a time. The
           only connection is that the temperature reading happened at a cer-
           tain time. You can use the GGAAUUGGEE data source type for this. RRDTool
           will the record your reading together with the time.

       Mail Messages
           Assume you have a method to count the number of messages trans-
           ported 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 AABBSSOOLLUUTTEE datatype 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 trans-
           ported 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 and ABSO-
           LUTE data.  When you plot the data, you will get on the y axis
           amount/second which you might be tempted to convert to absolute
           amount volume by multiplying by the delta-time between the points.
           RRDTool plots continuous data, and as such is not appropriate for
           plotting absolute volumes as for example "total bytes" sent and
           received in a router. What you probably want is plot rates that you
           can scale to for example bytes/hour or plot volumes 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).

EEXXAAMMPPLLEE
       "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 RRRRDD called _t_e_m_p_e_r_a_t_u_r_e_._r_r_d which accepts one tempera-
       ture value every 300 seconds. If no new data is supplied for more than
       600 seconds, the temperature becomes _*_U_N_K_N_O_W_N_*.  The minimum acceptable
       value is -273 and the maximum is 5000.

       A few archives areas are also defined. The first stores the tempera-
       tures supplied for 100 hours (1200 * 300 seconds = 100 hours). The sec-
       ond 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 for the maximum and average temperature,
       respectively.

AAUUTTHHOORR
       Tobias Oetiker <oetiker@ee.ethz.ch>



1.0.49                            2004-01-17                      RRDCREATE(1)
