


     RRRRRRRRDDDDCCCCRRRREEEEAAAATTTTEEEE((((1111))))           1111....2222....11113333 ((((2222000000006666----00005555----00004444))))           RRRRRRRRDDDDCCCCRRRREEEEAAAATTTTEEEE((((1111))))



     NNNNAAAAMMMMEEEE
          rrdcreate - Set up a new Round Robin Database

     SSSSYYYYNNNNOOOOPPPPSSSSIIIISSSS
          rrrrrrrrddddttttoooooooollll ccccrrrreeeeaaaatttteeee _f_i_l_e_n_a_m_e [--------ssssttttaaaarrrrtttt|----bbbb _s_t_a_r_t _t_i_m_e]
          [--------sssstttteeeepppp|----ssss _s_t_e_p] [DDDDSSSS::::_d_s-_n_a_m_e::::_D_S_T::::_d_s_t _a_r_g_u_m_e_n_t_s]
          [RRRRRRRRAAAA::::_C_F::::_c_f _a_r_g_u_m_e_n_t_s]

     DDDDEEEESSSSCCCCRRRRIIIIPPPPTTTTIIIIOOOONNNN
          The create function of RRDtool lets you set up new Round
          Robin Database (RRRRRRRRDDDD) 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 RRRRRRRRDDDD you want to create. RRRRRRRRDDDD files
                  should end with the extension ._r_r_d. However, RRRRRRRRDDDDttttoooooooollll
                  will accept any filename.

          --ssssttttaaaarrrrtttt|-bbbb _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 RRRRRRRRDDDD.
                  RRRRRRRRDDDDttttoooooooollll 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 other ways to specify
                  time.

          --sssstttteeeepppp|-ssss _s_t_e_p (default: 300 seconds)
                  Specifies the base interval in seconds with which
                  data will be fed into the RRRRRRRRDDDD.

          DDDDSSSS::::_d_s-_n_a_m_e::::_D_S_T::::_d_s_t _a_r_g_u_m_e_n_t_s
                  A single RRRRRRRRDDDD can accept input from several data
                  sources (DDDDSSSS), for example incoming and outgoing
                  traffic on a specific communication line. With the
                  DDDDSSSS configuration option you must define some basic
                  properties of each data source you want to store in
                  the RRRRRRRRDDDD.

                  _d_s-_n_a_m_e is the name you will use to reference this
                  particular data source from an RRRRRRRRDDDD. 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. The remaining
                  arguments of a data source entry depend on the data
                  source type. For GAUGE, COUNTER, DERIVE, and
                  ABSOLUTE the format for a data source entry is:

                  DDDDSSSS::::_d_s-_n_a_m_e::::_G_A_U_G_E | _C_O_U_N_T_E_R | _D_E_R_I_V_E |
                  _A_B_S_O_L_U_T_E::::_h_e_a_r_t_b_e_a_t::::_m_i_n::::_m_a_x



     Page 1                                          (printed 6/13/06)






     RRRRRRRRDDDDCCCCRRRREEEEAAAATTTTEEEE((((1111))))           1111....2222....11113333 ((((2222000000006666----00005555----00004444))))           RRRRRRRRDDDDCCCCRRRREEEEAAAATTTTEEEE((((1111))))



                  For COMPUTE data sources, the format is:

                  DDDDSSSS::::_d_s-_n_a_m_e::::_C_O_M_P_U_T_E::::_r_p_n-_e_x_p_r_e_s_s_i_o_n

                  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.

                  GGGGAAAAUUUUGGGGEEEE
                      is for things like temperatures or number of
                      people in a room or the value of a RedHat share.

                  CCCCOOOOUUUUNNNNTTTTEEEERRRR
                      is for continuous incrementing counters like the
                      ifInOctets counter in a router. The CCCCOOOOUUUUNNNNTTTTEEEERRRR 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.

                  DDDDEEEERRRRIIIIVVVVEEEE
                      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.

                      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



     Page 2                                          (printed 6/13/06)






     RRRRRRRRDDDDCCCCRRRREEEEAAAATTTTEEEE((((1111))))           1111....2222....11113333 ((((2222000000006666----00005555----00004444))))           RRRRRRRRDDDDCCCCRRRREEEEAAAATTTTEEEE((((1111))))



                          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.

                  AAAABBBBSSSSOOOOLLLLUUUUTTTTEEEE
                      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.

                  CCCCOOOOMMMMPPPPUUUUTTTTEEEE
                      is for storing the result of a formula applied
                      to other data sources in the RRRRRRRRDDDD. 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.

                  _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 define the expected range values for
                  data supplied by a data source. If _m_i_n and/or _m_a_x
                  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-CCCCOOOOUUUUNNNNTTTTEEEERRRR type DS this would be the
                  maximum and minimum 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.




     Page 3                                          (printed 6/13/06)






     RRRRRRRRDDDDCCCCRRRREEEEAAAATTTTEEEE((((1111))))           1111....2222....11113333 ((((2222000000006666----00005555----00004444))))           RRRRRRRRDDDDCCCCRRRREEEEAAAATTTTEEEE((((1111))))



                  _r_p_n-_e_x_p_r_e_s_s_i_o_n 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 CCCCDDDDEEEEFFFF 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 CCCCDDDDEEEEFFFFs must refer only to DDDDEEEEFFFFs
                  and CCCCDDDDEEEEFFFFs previously defined in the same graph
                  command.

          RRRRRRRRAAAA::::_C_F::::_c_f _a_r_g_u_m_e_n_t_s
                  The purpose of an RRRRRRRRDDDD is to store data in the round
                  robin archives (RRRRRRRRAAAA). An archive consists of a
                  number of data values or statistics for each of the
                  defined data-sources (DDDDSSSS) and is defined with an RRRRRRRRAAAA
                  line.

                  When data is entered into an RRRRRRRRDDDD, it is first fit
                  into time slots of the length defined with the ----ssss
                  option, thus becoming a _p_r_i_m_a_r_y _d_a_t_a _p_o_i_n_t.

                  The data is also processed with the consolidation
                  function (_C_F) of the archive. There are several
                  consolidation functions that consolidate primary
                  data points via an aggregate function: AAAAVVVVEEEERRRRAAAAGGGGEEEE, MMMMIIIINNNN,
                  MMMMAAAAXXXX, LLLLAAAASSSSTTTT. The format of RRRRRRRRAAAA line for these
                  consolidation functions is:

                  RRRRRRRRAAAA::::_A_V_E_R_A_G_E | _M_I_N | _M_A_X | _L_A_S_T::::_x_f_f::::_s_t_e_p_s::::_r_o_w_s

                  _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 consolidated value is still regarded
                  as known. It is given as the ratio of allowed
                  *_U_N_K_N_O_W_N* PDPs to the number of PDPs in the
                  interval. Thus, it ranges from 0 to 1 (exclusive).

                  _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 RRRRRRRRAAAA.

     AAAAbbbbeeeerrrrrrrraaaannnntttt BBBBeeeehhhhaaaavvvviiiioooorrrr DDDDeeeetttteeeeccccttttiiiioooonnnn wwwwiiiitttthhhh HHHHoooolllltttt----WWWWiiiinnnntttteeeerrrrssss FFFFoooorrrreeeeccccaaaassssttttiiiinnnngggg
          In addition to the aggregate functions, there are a set of
          specialized functions that enable RRRRRRRRDDDDttttoooooooollll to provide data



     Page 4                                          (printed 6/13/06)






     RRRRRRRRDDDDCCCCRRRREEEEAAAATTTTEEEE((((1111))))           1111....2222....11113333 ((((2222000000006666----00005555----00004444))))           RRRRRRRRDDDDCCCCRRRREEEEAAAATTTTEEEE((((1111))))



          smoothing (via the Holt-Winters forecasting algorithm),
          confidence bands, and the flagging aberrant behavior in the
          data source time series:

          +o   RRRRRRRRAAAA::::_H_W_P_R_E_D_I_C_T::::_r_o_w_s::::_a_l_p_h_a::::_b_e_t_a::::_s_e_a_s_o_n_a_l _p_e_r_i_o_d[::::_r_r_a-_n_u_m]

          +o   RRRRRRRRAAAA::::_S_E_A_S_O_N_A_L::::_s_e_a_s_o_n_a_l _p_e_r_i_o_d::::_g_a_m_m_a::::_r_r_a-_n_u_m

          +o   RRRRRRRRAAAA::::_D_E_V_S_E_A_S_O_N_A_L::::_s_e_a_s_o_n_a_l _p_e_r_i_o_d::::_g_a_m_m_a::::_r_r_a-_n_u_m

          +o   RRRRRRRRAAAA::::_D_E_V_P_R_E_D_I_C_T::::_r_o_w_s::::_r_r_a-_n_u_m

          +o   RRRRRRRRAAAA::::_F_A_I_L_U_R_E_S::::_r_o_w_s::::_t_h_r_e_s_h_o_l_d::::_w_i_n_d_o_w _l_e_n_g_t_h::::_r_r_a-_n_u_m

          These RRRRRRRRAAAAssss differ from the true consolidation functions in
          several ways.  First, each of the RRRRRRRRAAAAs is updated once for
          every primary data point.  Second, these RRRRRRRRAAAAssss are
          interdependent. To generate real-time confidence bounds, a
          matched set of HWPREDICT, SEASONAL, DEVSEASONAL, and
          DEVPREDICT must exist. Generating smoothed values of the
          primary data points requires both a HWPREDICT RRRRRRRRAAAA and
          SEASONAL RRRRRRRRAAAA. Aberrant behavior detection requires FAILURES,
          HWPREDICT, DEVSEASONAL, and SEASONAL.

          The actual predicted, or smoothed, values are stored in the
          HWPREDICT RRRRRRRRAAAA. The predicted deviations are stored in
          DEVPREDICT (think a standard deviation which can be scaled
          to yield a confidence band). The FAILURES RRRRRRRRAAAA 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 RRRRRRRRAAAAssss to graph
          confidence bounds and failures appears in rrdgraph.

          The SEASONAL and DEVSEASONAL RRRRRRRRAAAAssss 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 RRRRRRRRAAAAssss, the
          RRRRRRRRDDDDttttoooooooollll create command supports implicit creation of the
          other four when HWPREDICT is specified alone and the final
          argument _r_r_a-_n_u_m is omitted.

          _r_o_w_s specifies the length of the RRRRRRRRAAAA prior to wrap around.
          Remember that there is a one-to-one correspondence between
          primary data points and entries in these RRAs. For the



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     RRRRRRRRDDDDCCCCRRRREEEEAAAATTTTEEEE((((1111))))           1111....2222....11113333 ((((2222000000006666----00005555----00004444))))           RRRRRRRRDDDDCCCCRRRREEEEAAAATTTTEEEE((((1111))))



          HWPREDICT CF, _r_o_w_s should be larger than the _s_e_a_s_o_n_a_l
          _p_e_r_i_o_d. If the DEVPREDICT RRRRRRRRAAAA is implicitly created, the
          default number of rows is the same as the HWPREDICT _r_o_w_s
          argument. If the FAILURES RRRRRRRRAAAA is implicitly created, _r_o_w_s
          will be set to the _s_e_a_s_o_n_a_l _p_e_r_i_o_d argument of the HWPREDICT
          RRRRRRRRAAAA. Of course, the RRRRRRRRDDDDttttoooooooollll _r_e_s_i_z_e command is available if
          these defaults are not sufficient and the creator wishes to
          avoid explicit creations of the other specialized function
          RRRRRRRRAAAAssss.

          _s_e_a_s_o_n_a_l _p_e_r_i_o_d specifies the number of primary data points
          in a seasonal cycle. If SEASONAL and DEVSEASONAL are
          implicitly created, this argument for those RRRRRRRRAAAAssss is set
          automatically to the value specified by HWPREDICT. If they
          are explicitly created, the creator should verify that all
          three _s_e_a_s_o_n_a_l _p_e_r_i_o_d arguments agree.

          _a_l_p_h_a is the adaption parameter of the intercept (or
          baseline) coefficient in the Holt-Winters forecasting
          algorithm. See rrdtool for a description of this algorithm.
          _a_l_p_h_a 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.

          _b_e_t_a is the adaption parameter of the slope (or linear
          trend) coefficient in the Holt-Winters forecasting
          algorithm. _b_e_t_a must lie between 0 and 1 and plays the same
          role as _a_l_p_h_a with respect to the predicted linear trend.

          _g_a_m_m_a 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 RRRRRRRRAAAAssss are created implicitly, they
          will both have the same value for _g_a_m_m_a: the value specified
          for the HWPREDICT _a_l_p_h_a 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 RRRRRRRRAAAAssss are created explicitly,
          _g_a_m_m_a need not be the same for both. Note that _g_a_m_m_a can
          also be changed via the RRRRRRRRDDDDttttoooooooollll _t_u_n_e command.

          _r_r_a-_n_u_m provides the links between related RRRRRRRRAAAAssss. If
          HWPREDICT is specified alone and the other RRRRRRRRAAAAssss are created
          implicitly, then there is no need to worry about this



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     RRRRRRRRDDDDCCCCRRRREEEEAAAATTTTEEEE((((1111))))           1111....2222....11113333 ((((2222000000006666----00005555----00004444))))           RRRRRRRRDDDDCCCCRRRREEEEAAAATTTTEEEE((((1111))))



          argument. If RRRRRRRRAAAAssss are created explicitly, then carefully pay
          attention to this argument. For each RRRRRRRRAAAA which includes this
          argument, there is a dependency between that RRRRRRRRAAAA and another
          RRRRRRRRAAAA. The _r_r_a-_n_u_m argument is the 1-based index in the order
          of RRRRRRRRAAAA creation (that is, the order they appear in the
          _c_r_e_a_t_e command). The dependent RRRRRRRRAAAA for each RRRRRRRRAAAA requiring
          the _r_r_a-_n_u_m argument is listed here:

          +o   HWPREDICT _r_r_a-_n_u_m is the index of the SEASONAL RRRRRRRRAAAA.

          +o   SEASONAL _r_r_a-_n_u_m is the index of the HWPREDICT RRRRRRRRAAAA.

          +o   DEVPREDICT _r_r_a-_n_u_m is the index of the DEVSEASONAL RRRRRRRRAAAA.

          +o   DEVSEASONAL _r_r_a-_n_u_m is the index of the HWPREDICT RRRRRRRRAAAA.

          +o   FAILURES _r_r_a-_n_u_m is the index of the DEVSEASONAL RRRRRRRRAAAA.

          _t_h_r_e_s_h_o_l_d is the minimum number of violations (observed
          values outside the confidence bounds) within a window that
          constitutes a failure. If the FAILURES RRRRRRRRAAAA is implicitly
          created, the default value is 7.

          _w_i_n_d_o_w _l_e_n_g_t_h 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 RRRRRRRRAAAA is implicitly created, the
          default value is 9.

     TTTThhhheeee HHHHEEEEAAAARRRRTTTTBBBBEEEEAAAATTTT aaaannnndddd tttthhhheeee SSSSTTTTEEEEPPPP
          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 at arbitrary times. From these it
          builds Primary Data Points (PDPs) at exact times on 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 limits, 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



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     RRRRRRRRDDDDCCCCRRRREEEEAAAATTTTEEEE((((1111))))           1111....2222....11113333 ((((2222000000006666----00005555----00004444))))           RRRRRRRRDDDDCCCCRRRREEEEAAAATTTTEEEE((((1111))))



          means that a mixture of known and "unknown" sample times 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 samples, 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
          "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. -- _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>



































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     RRRRRRRRDDDDCCCCRRRREEEEAAAATTTTEEEE((((1111))))           1111....2222....11113333 ((((2222000000006666----00005555----00004444))))           RRRRRRRRDDDDCCCCRRRREEEEAAAATTTTEEEE((((1111))))



                 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" labled secs > "hb"
                  |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 _v_l_a_d_i_m_i_r._l_a_v_r_o_v@_d_e_s_y._d_e.

     HHHHOOOOWWWW TTTTOOOO MMMMEEEEAAAASSSSUUUURRRREEEE
          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 GGGGAAAAUUUUGGGGEEEE 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 mailserver in a certain amount of



     Page 9                                          (printed 6/13/06)






     RRRRRRRRDDDDCCCCRRRREEEEAAAATTTTEEEE((((1111))))           1111....2222....11113333 ((((2222000000006666----00005555----00004444))))           RRRRRRRRDDDDCCCCRRRREEEEAAAATTTTEEEE((((1111))))



              time, giving you data like '5 messages in the last 65
              seconds'. If you look at the count of 5 like an AAAABBBBSSSSOOOOLLLLUUUUTTTTEEEE
              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 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).

     EEEEXXXXAAAAMMMMPPPPLLLLEEEE
           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 RRRRRRRRDDDD called _t_e_m_p_e_r_a_t_u_r_e._r_r_d which accepts one
          temperature 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 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.

     EEEEXXXXAAAAMMMMPPPPLLLLEEEE 2222




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     RRRRRRRRDDDDCCCCRRRREEEEAAAATTTTEEEE((((1111))))           1111....2222....11113333 ((((2222000000006666----00005555----00004444))))           RRRRRRRRDDDDCCCCRRRREEEEAAAATTTTEEEE((((1111))))



           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
          RRRRRRRRAAAA tracks the traffic flow in octets; the second RRRRRRRRAAAA
          generates the specialized functions RRRRRRRRAAAAssss for aberrant
          behavior detection. Note that the _r_r_a-_n_u_m argument of
          HWPREDICT is missing, so the other RRRRRRRRAAAAssss 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 RRRRRRRRAAAA.

          The same RRD file and RRRRRRRRAAAAssss are created with the following
          command, which explicitly creates all specialized function
          RRRRRRRRAAAAssss.

           rrdtool create monitor.rrd --step 300 \
             DS:ifOutOctets:COUNTER:1800:0:4294967295 \
             RRA:AVERAGE:0.5:1:2016 \
             RRA:HWPREDICT:1440:0.1:0.0035:288:3 \
             RRA:SEASONAL:288:0.1:2 \
             RRA:DEVPREDICT:1440:5 \
             RRA:DEVSEASONAL:288:0.1:2 \
             RRA:FAILURES:288:7:9:5

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

     EEEEXXXXAAAAMMMMPPPPLLLLEEEE 3333
           rrdtool create proxy.rrd --step 300 \
             DS:Total: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



     Page 11                                         (printed 6/13/06)






     RRRRRRRRDDDDCCCCRRRREEEEAAAATTTTEEEE((((1111))))           1111....2222....11113333 ((((2222000000006666----00005555----00004444))))           RRRRRRRRDDDDCCCCRRRREEEEAAAATTTTEEEE((((1111))))



          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 RRRRRRRRDDDD, 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.

     AAAAUUUUTTTTHHHHOOOORRRR
          Tobias Oetiker <tobi@oetiker.ch>





































     Page 12                                         (printed 6/13/06)



