RRDTOOL(1)                          rrdtool                         RRDTOOL(1)



NNAAMMEE
       rrdtool - round robin database tool

SSYYNNOOPPSSIISS
       rrrrddttooooll -- | _f_u_n_c_t_i_o_n

DDEESSCCRRIIPPTTIIOONN
       OOVVEERRVVIIEEWW

       It is pretty easy to gather status information from all sorts of
       things, ranging from the temperature in your office to the number of
       octets which have passed through the FDDI interface of your router. But
       it is not so trivial to store this data in a efficient and systematic
       manner. This is where rrrrddttooooll kicks in. It lets you _l_o_g _a_n_d _a_n_a_l_y_z_e the
       data you gather from all kinds of data-sources (DDSS). The data analysis
       part of rrdtool is based on the ability to quickly generate graphical
       representations of the data values collected over a definable time
       period.

       In this man page you will find general information on the design and
       functionality of the Round Robin Database Tool (rrdtool). For a more
       detailed description of how to use the individual functions of the rrrrdd--
       ttooooll check the corresponding man page.

       For an introduction to the usage of rrdtool make sure you check rrdtu-
       torial.

       FFUUNNCCTTIIOONNSS

       While the man pages talk of command line switches you have to set in
       order to make rrrrddttooooll work it is important to note that the rrrrddttooooll can
       be 'remote controlled' through a set of pipes. This saves a consider-
       able amount of startup time when you plan to make rrrrddttooooll do a lot of
       things quickly. Check the section on "Remote Control" further down.
       There is also a number of language bindings for rrdtool which allow you
       to use it directly from perl, python, tcl, php, ...

       ccrreeaattee  Set up a new Round Robin Database (RRD). Check rrdcreate.

       uuppddaattee  Store new data values into an RRD. Check rrdupdate.

       ggrraapphh   Create a graph from data stored in one or several RRD. Apart
               from generating graphs, data can also be extracted to stdout.
               Check rrdgraph.

       dduummpp    Dump the contents of an RRD in plain ASCII. In connection with
               restore you can use it to transport an rrd from one architec-
               ture to another.  Check rrddump.

       rreessttoorree Restore an RRD in XML format to a binary rrd ... Check
               rrdrestore

       ffeettcchh   Get data for a certain time period from a RRD. The graph func-
               tion uses fetch to retrieve its data from an rrd. Check rrd-
               fetch.

       ttuunnee    Alter setup of an RRD. Check rrdtune.

       llaasstt    Find last update time of an RRD. Check rrdlast.

       iinnffoo    Display information about an RRD ... Check rrdinfo

       rrrrddrreessiizzee
               Change the size of individual RRAs ... Dangerous! Check rrdre-
               size.

       xxppoorrtt   Export data retrieved from one or several RRD. Check rrdxport

       rrrrddccggii  This is a standalone tool for producing rrd graphs on the fly.
               Check rrdcgi.

       HHOOWW DDOOEESS RRRRDDTTOOOOLL WWOORRKK??


       Data acquisition
               When monitoring the state of a system, it is convenient to have
               the data available at a constant interval. Unfortunately you
               may not always be able to fetch data at exactly the time you
               want to. Therefore rrrrddttooooll lets you update the logfile at any
               time you want. It will automatically interpolate the value of
               the data-source (DDSS) at the latest official time-slot and write
               this value to the log. The value you have supplied is stored as
               well and is also taken into account when interpolating the next
               log entry.

       Consolidation
               You may log data at a 1 minute interval, but you are also be
               interested to know the development of the data over the last
               year. You could do this by simply storing the data in 1 minute
               interval, for one year. While this would take considerable disk
               space it would also take a lot of time to analyze the data when
               you wanted to create a graph covering the whole year. rrrrddttooooll
               offers a solution to this problem through its data consolida-
               tion feature. When setting up an Round Robin Database (RRRRDD),
               you can define at which interval this consolidation should
               occur, and what consolidation function (CCFF) (average, minimum,
               maximum, last) should be used to build the consolidated values
               (see rrdcreate). You can define any number of different consol-
               idation setups within one RRRRDD. They will all be maintained on
               the fly when new data is loaded into the RRRRDD.

       Round Robin Archives
               Data values of the same consolidation setup are stored into
               Round Robin Archives (RRRRAA). This is a very efficient manner to
               store data for a certain amount of time, while using a known
               amount of storage space.

               It works like this: If you want to store 1000 values in 5
               minute interval, rrrrddttooooll will allocate space for 1000 data val-
               ues and a header area. In the header it will store a pointer
               telling which one of the values in the storage area was last
               written to. New values are written to the Round Robin Archive
               in a ...  you guess it ... round robin manner. This automati-
               cally limits the history to the last 1000 values. Because you
               can define several RRRRAAs within a single RRRRDD, you can setup
               another one, storing 750 data values at a 2 hour interval and
               thus keeping a log for the last two months although at a lower
               resolution.

               The use of RRRRAAs guarantees that the RRRRDD does not grow over time
               and that old data is automatically eliminated. By using the
               consolidation feature, you can still keep data for a very long
               time, while gradually reducing the resolution of the data along
               the time axis. Using different consolidation functions (CCFF)
               allows you to store exactly the type of information that actu-
               ally interests you. (Maximum one minute traffic on the LAN,
               minimum temperature of the wine cellar, total minutes down time
               ...)

       Unknown Data
               As mentioned earlier, the RRRRDD stores data at a constant inter-
               val. Now it may happen that no new data is available when a
               value has to be written to the RRRRDD. Data acquisition may not be
               possible for one reason or an other. The rrrrddttooooll handles these
               situations by storing an _*_U_N_K_N_O_W_N_* value into the database. The
               value '_*_U_N_K_N_O_W_N_*' is supported through all the functions of the
               database. When consolidating the amount of _*_U_N_K_N_O_W_N_* data is
               accumulated and when a new consolidated value is ready to be
               written to its Round Robin Archive (RRRRAA) a validity check is
               performed to make sure that the percentage of unknown data in
               the new value is below a configurable level. If so, an
               _*_U_N_K_N_O_W_N_* value will be written to the RRRRAA.

       Graphing
               The rrrrddttooooll also allows one to generate reports in numerical
               and graphical form based on the data stored in one or several
               RRRRDDs. The graphing feature is fully configurable. Size, color
               and contents of the graph can be defined freely. Check rrdgraph
               for more information on this.

       RREEMMOOTTEE CCOONNTTRROOLL

       When you start rrrrddttooooll with the command line option '--', it waits for
       input via standard in. With this feature you can improve performance by
       attaching rrrrddttooooll to another process (mrtg is one example) through a
       set of pipes. Over the pipes rrrrddttooooll accepts the same arguments as on
       the command line. When a command is completed, rrdtool will print the
       string  '"OK"', followed by timing information of the form uu::_u_s_e_r_t_i_m_e
       ss::_s_y_s_t_e_m_t_i_m_e both values are running totals of seconds since rrdtool
       was started. If an error occurs, a line of the form '"ERROR:" _D_e_s_c_r_i_p_-
       _t_i_o_n _o_f _e_r_r_o_r' will be printed. rrrrddttooooll will not abort if possible, but
       follow the ERROR line with an OK line.

SSEEEE AALLSSOO
       rrdcreate, rrdupdate, rrdgraph, rrddump, rrdfetch, rrdtune, rrdlast,
       rrdxport

BBUUGGSS
       Bugs ? Features !

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



1.0.45                            2002-11-29                        RRDTOOL(1)
