_R_R_D_C_A_C_H_E_D(1)                        rrdtool                       _R_R_D_C_A_C_H_E_D(1)

NNAAMMEE
       rrdcached - Data caching daemon for rrdtool

SSYYNNOOPPSSIISS
       rrrrddccaacchheedd [--aa _a_l_l_o_c___s_i_z_e] [--bb _b_a_s_e___d_i_r [--BB]] [--FF] [--ff _t_i_m_e_o_u_t]
       [--GG _g_r_o_u_p]] [--gg] [--jj _j_o_u_r_n_a_l___d_i_r] [--LL] [--ll _a_d_d_r_e_s_s] [--mm _m_o_d_e] [--OO]
       [--oo _l_o_g___f_i_l_e] [--PP _p_e_r_m_i_s_s_i_o_n_s] [--pp _p_i_d___f_i_l_e] [--RR] [--ss _g_r_o_u_p]
       [--tt _w_r_i_t_e___t_h_r_e_a_d_s] [--UU _u_s_e_r]] [--VV _l_o_g___l_e_v_e_l] [--ww _t_i_m_e_o_u_t] [--zz _d_e_l_a_y]

DDEESSCCRRIIPPTTIIOONN
       rrrrddccaacchheedd is a daemon that receives updates to existing RRD files,
       accumulates them and, if enough have been received or a defined time
       has passed, writes the updates to the RRD file. A _f_l_u_s_h command may be
       used to force writing of values to disk, so that graphing facilities
       and similar can work with up-to-date data.

       The daemon was written with big setups in mind. Those setups usually
       run into IO related problems sooner or later for reasons that are
       beyond the scope of this document. Check the wiki at the RRDtool
       homepage for details. Also check "SECURITY CONSIDERATIONS" below before
       using this daemon! A detailed description of how the daemon operates
       can be found in the "HOW IT WORKS" section below.

OOPPTTIIOONNSS
       --ll _a_d_d_r_e_s_s
           Tells  the  daemon  to  bind  to  _a_d_d_r_e_s_s  and  accept incoming TCP
           connections  on  that  socket.  If  _a_d_d_r_e_s_s  begins  with  "unix:",
           everything  following  that  prefix is interpreted as the path to a
           UNIX domain socket. Otherwise the address or node name are resolved
           using getaddrinfo().

           For network sockets, a port may be  specified  by  using  the  form
           "[[_a_d_d_r_e_s_s]]::_p_o_r_t".  If  the  address  is  an IPv4 address or a fully
           qualified domain name (i. e. the address contains at least one  dot
           (".")),  the  square  brackets  can  be  omitted,  resulting in the
           (simpler) "_a_d_d_r_e_s_s::_p_o_r_t" pattern. The default port is 4422221177. If you
           specify a network socket, it is mandatory  to  read  the  "SECURITY
           CONSIDERATIONS" section.

           The following formats are accepted. Please note that the address of
           the UNIX domain socket mmuusstt start with a slash in the second case!

              unix:</path/to/unix.sock>
              /<path/to/unix.sock>
              <hostname-or-ip>
              [<hostname-or-ip>]:<port>
              <hostname-or-ipv4>:<port>

           Given  a  port  without  a  host (e.g. "-l :42217") the daemon will
           listen on that port on all network interfaces.  Use "-L"  to  avoid
           the  need  to  explicitly  provide  the port if the default port is
           desired.

           If  no  --ll  option  is   not   specified   the   default   address,
           "unix:/tmp/rrdcached.sock",  will be used.  Multiple --ll options may
           be provided.

       --LL  Tells the daemon to bind to the default TCP port on  all  available
           interfaces.   It  is equivalent to "-l ''" without the confusion of
           the empty string parameter.

       --ss _g_r_o_u_p___n_a_m_e|_g_i_d
           Set the group permissions of  a  UNIX  domain  socket.  The  option
           accepts  either  a  numeric group id or group name. That group will
           then have both read and write permissions  (the  socket  will  have
           file  permissions  0760)  for the socket and, therefore, is able to
           send commands to the daemon. This may be useful in cases where  you
           cannot  easily  run all RRD processes with the same user privileges
           (e.g. graph generating  CGI  scripts  that  typically  run  in  the
           permission context of the web server).

           This  option  affects  the  _f_o_l_l_o_w_i_n_g  UNIX  socket  addresses (the
           following --ll options) or the default socket (if no --ll options  have
           been  specified),  i.e.,  you  may  specify  different settings for
           different sockets.

           The default is not to change ownership or permissions of the socket
           and, thus, use the system default.

       --mm _m_o_d_e
           Set the file permissions  of  a  UNIX  domain  socket.  The  option
           accepts  an  octal number representing the bit pattern for the mode
           (see cchhmmoodd(1) for details).

           Please note that not all systems  honor  this  setting.  On  Linux,
           read/write  permissions  are  required to connect to a UNIX socket.
           However, many  BSD-derived  systems  ignore  permissions  for  UNIX
           sockets. See uunniixx(7) for details.

           This  option  affects  the  _f_o_l_l_o_w_i_n_g  UNIX  socket  addresses (the
           following --ll options) or the default socket (if no --ll options  have
           been  specified),  i.e.,  you  may  specify  different settings for
           different sockets.

           The default is not to change ownership or permissions of the socket
           and, thus, use the system default.

       --PP _c_o_m_m_a_n_d[,_c_o_m_m_a_n_d[,...]]
           Specifies the commands accepted via  both  a  network  and  a  UNIX
           socket.  This  allows  administrators  of  _R_R_D_C_a_c_h_e_D to control the
           actions accepted from various sources.

           The arguments given to the --PP option is a comma separated  list  of
           commands.   For  example,  to  allow  one the "FLUSH" and "PENDING"
           commands one could specify:

             rrdcached -P FLUSH,PENDING $MORE_ARGUMENTS

           The --PP option affects the _f_o_l_l_o_w_i_n_g socket addresses (the following
           --ll options) or the default socket  (if  no  --ll  options  have  been
           specified).  In the following example, only the IPv4 network socket
           (address 10.0.0.1) will be restricted to the "FLUSH" and  "PENDING"
           commands:

             rrdcached -l unix:/some/path -P FLUSH,PENDING -l 10.0.0.1

           A  complete  list of available commands can be found in the section
           "Valid Commands" below. There are two minor special exceptions:

           •   The "HELP" and "QUIT" commands are always allowed.

           •   If  the  "BATCH"  command  is  accepted,  the  .. command   will
               automatically be accepted, too.

           Please also read "SECURITY CONSIDERATIONS" below.

       --VV _l_o_g___l_e_v_e_l
           rrdcached under load can severely flood the logs. This command line
           option  specifies  the maximum log_level to be used, meaning that a
           message with verbosity _h_i_g_h_e_r than log_level  is  muted  (LOG_EMERG
           being the lowest and LOG_DEBUG highest).

           Accepted  values  for  "log_level"  (lowest  to highest verbosity):
           LOG_EMERG, LOG_ALERT, LOG_CRIT, LOG_ERR,  LOG_WARNING,  LOG_NOTICE,
           LOG_INFO, LOG_DEBUG

           Default log level when this flag is _N_O_T present: LLOOGG__EERRRR

           See also: _s_y_s_l_o_g_._h

       --oo _l_o_g___f_i_l_e
           Log to the given file instead of syslog.

       --ww _t_i_m_e_o_u_t
           Data  is written to disk every _t_i_m_e_o_u_t seconds.  An optional suffix
           may be used (e.g. "5m" instead of 300 seconds).  If this option  is
           not specified the default interval of 300 seconds will be used.

       --zz _d_e_l_a_y
           If specified, rrdcached will delay writing of each RRD for a random
           number of seconds in the range [0,_d_e_l_a_y).  This will avoid too many
           writes  being  queued  simultaneously.   This  value  should  be no
           greater than the value specified in --ww.  An optional suffix may  be
           used  (e.g.  "3m" instead of 180 seconds).  By default, there is no
           delay.

       --ff _t_i_m_e_o_u_t
           Every _t_i_m_e_o_u_t seconds the entire cache is searched for  old  values
           which  are  written  to  disk.  This  only  concerns files to which
           updates have stopped, so setting this to  a  high  value,  such  as
           3600 seconds,  is acceptable in most cases.  An optional suffix may
           be used (e.g. "1h" instead of 3600 seconds).  This timeout defaults
           to 3600 seconds.

       --pp _f_i_l_e
           Sets the name and location of the PID-file. If not  specified,  the
           default, "_$_l_o_c_a_l_s_t_a_t_e_d_i_r/run/rrdcached.pid" will be used.

       --tt _w_r_i_t_e___t_h_r_e_a_d_s
           Specifies  the  number  of threads used for writing RRD files.  The
           default is 4.  Increasing this number will allow rrdcached to  have
           more simultaneous I/O requests into the kernel.  This may allow the
           kernel   to   re-order   disk  writes,  resulting  in  better  disk
           throughput.

       --jj _d_i_r
           Write updates to a journal in _d_i_r.  In the event of  a  program  or
           system  crash, this will allow the daemon to write any updates that
           were pending at the time of the crash.

           On startup, the  daemon  will  check  for  journal  files  in  this
           directory.   If found, all updates therein will be read into memory
           before the daemon starts accepting new connections.

           The journal will be rotated with the same frequency  as  the  flush
           timer given by --ff.

           When  journaling  is  enabled,  the daemon will use a fast shutdown
           procedure.  Rather than flushing all files to disk,  it  will  make
           sure   the  journal  is  properly  written  and  exit  immediately.
           Although  the  RRD  data  files  are  not  fully   up-to-date,   no
           information  is lost; all pending updates will be replayed from the
           journal next time the daemon starts up.

           To disable fast shutdown, use the --FF option.

       --FF  ALWAYS flush all updates to the RRD data files when the  daemon  is
           shut down, regardless of journal setting.

       --gg  Run in the foreground.  The daemon will not ffoorrkk(()).

       --bb _d_i_r
           The  daemon  will  change into a specific directory at startup. All
           files passed to the daemon, that are specified by a rreellaattiivvee  path,
           will  be interpreted to be relative to this directory. If not given
           the default, "/tmp", will be used.

             +------------------------+------------------------+
             ! Command line           ! File updated           !
             +------------------------+------------------------+
             ! foo.rrd                ! /tmp/foo.rrd           !
             ! foo/bar.rrd            ! /tmp/foo/bar.rrd       !
             ! /var/lib/rrd/foo.rrd   ! /var/lib/rrd/foo.rrd   !
             +------------------------+------------------------+
             Paths given on the command  line and paths actually
             updated by the daemon,  assuming the base directory
             "/tmp".

           WWAARRNNIINNGG:: The paths up to and including the base directory MMUUSSTT  NNOOTT
           BBEE  symbolic  links.   In  other  words,  if  the base directory is
           specified as:

               -b /base/dir/somewhere

           ... then NNOONNEE of the following should be symbolic links:

               /base
               /base/dir
               /base/dir/somewhere

       --BB  Only permit writes into the base directory specified in --bb (and any
           sub-directories).  This does  NNOOTT  detect  symbolic  links.   Paths
           containing "../" will also be blocked.

       --RR  Permit  recursive  subdirectory  creation  in  the  base  directory
           specified in --bb (and any sub-directories). Can only be used when --BB
           is also set.

       --aa _a_l_l_o_c___s_i_z_e
           Allocate value pointers in chunks of _a_l_l_o_c___s_i_z_e.  This may  improve
           CPU utilization on machines with slow realloc() implementations, in
           exchange for slightly higher memory utilization.  The default is 1.
           Do  not set this more than the --ww value divided by your average RRD
           step size.

       --OO  Prevent the CREATE command from overwriting  existing  files,  even
           when it is instructed to do so.  This is for added security.

       --GG -_g_r_o_u_p
           When running as daemon and invoked from a privileged account, reset
           group  privileges to those of _g_r_o_u_p.  The group may be specified as
           a name or as a group ID.  The daemon will exit with a diagnostic if
           it cannot successfully transition to the specified group.

       --UU -_u_s_e_r
           When running as daemon and invoked from a privileged account, reset
           user privileges to those of _u_s_e_r.  The user may be specified  as  a
           name or as a user ID.  The daemon will exit with a diagnostic if it
           cannot successfully transition to the specified user.

AAFFFFEECCTTEEDD RRRRDDTTOOOOLL CCOOMMMMAANNDDSS
       The  following  commands  may  be made aware of the rrrrddccaacchheedd using the
       command  line   argument   ----ddaaeemmoonn   or   the   environment   variable
       RRRRDDCCAACCHHEEDD__AADDDDRREESSSS:

       •   dump

       •   fetch

       •   flush

       •   graph

       •   graphv

       •   info

       •   first

       •   last

       •   lastupdate

       •   update

       •   xport

       •   create

       •   list

       The  uuppddaattee  command  can  send values to the daemon instead of writing
       them to the disk itself. All other commands can send  a  FFLLUUSSHH  command
       (see below) to the daemon before accessing the files, so they work with
       up-to-date data even if the cache timeout is large.

EERRRROORR RREEPPOORRTTIINNGG
       The  daemon  reports  errors  in one of two ways: During startup, error
       messages are printed to "STDERR". One of the steps when starting up  is
       to  fork  to  the  background and closing "STDERR" - after this writing
       directly to the user is no longer possible. Once this has happened, the
       daemon will send log  messages  to  the  system  logging  daemon  using
       ssyysslloogg(3). The facility used is "LOG_DAEMON".

HHOOWW IITT WWOORRKKSS
       When  receiving  an  update, rrrrddccaacchheedd does not write to disk but looks
       for an entry for that file in its internal tree. If not found, an entry
       is created including the current time (called "First"  in  the  diagram
       below). This time is nnoott the time specified on the command line but the
       time  the operating system considers to be "now". The value and time of
       the value (called "Time" in the diagram below) are appended to the tree
       node.

       When appending a value to a tree node, it is checked whether it's  time
       to   write   the  values  to  disk.  Values  are  written  to  disk  if
       "now() - First >= timeout", where "timeout" is  the  timeout  specified
       using the --ww option, see "OPTIONS". If the values are "old enough" they
       will  be enqueued in the "update queue", i. e. they will be appended to
       the linked list shown below.  Because the tree nodes and  the  elements
       of  the  linked list are the same data structures in memory, any update
       to a file that has already been enqueued will be written with the  next
       write to the RRD file, too.

       A separate "update thread" constantly dequeues the first element in the
       update  queue  and writes all its values to the appropriate file. So as
       long as the update queue is not empty files are written at the  highest
       possible rate.

       Since the timeout of files is checked only when new values are added to
       the file, "dead" files, i. e. files that are not updated anymore, would
       never  be written to disk. Therefore, every now and then, controlled by
       the --ff option, the entire tree is  walked  and  all  "old"  values  are
       enqueued.  Since this only affects "dead" files and walking the tree is
       relatively  expensive,  you  should  set  the  "flush  interval"  to  a
       reasonably high value. The default is 3600 seconds (one hour).

       The  downside  of  caching  values is that they won't show up in graphs
       generated from the RRD files. To get around this, the  daemon  provides
       the  "flush  command" to flush specific files. This means that the file
       is inserted at the hheeaadd of the update queue or moved  there  if  it  is
       already  enqueued.  The flush command will return only after the file's
       pending updates have been written to disk.

        +------+   +------+                               +------+
        ! head !   ! root !                               ! tail !
        +---+--+   +---+--+                               +---+--+
            !         /\                                      !
            !        /  \                                     !
            !       /\  /\                                    !
            !      /\/\ \ `----------------- ... --------,    !
            V     /      `-------,                       !    V
        +---+----+---+    +------+-----+             +---+----+---+
        ! File:  foo !    ! File:  bar !             ! File:  qux !
        ! First: 101 !    ! First: 119 !             ! First: 180 !
        ! Next:&bar -+--->! Next:&... -+---> ... --->! Next:NULL  !
        | Prev:NULL  !<---+-Prev:&foo  !<--- ... ----+-Prev: &... !
        +============+    +============+             +============+
        ! Time:  100 !    ! Time:  120 !             ! Time:  180 !
        ! Value:  10 !    ! Value: 0.1 !             ! Value: 2,2 !
        +------------+    +------------+             +------------+
        ! Time:  110 !    ! Time:  130 !             ! Time:  190 !
        ! Value:  26 !    ! Value: 0.1 !             ! Value: 7,3 !
        +------------+    +------------+             +------------+
        :            :    :            :             :            :
        +------------+    +------------+             +------------+
        ! Time:  230 !    ! Time:  250 !             ! Time:  310 !
        ! Value:  42 !    ! Value: 0.2 !             ! Value: 1,2 !
        +------------+    +------------+             +------------+

       The above diagram demonstrates:

       •   Files/values are stored in a (balanced) tree.

       •   Tree nodes and entries in  the  update  queue  are  the  same  data
           structure.

       •   The local time ("First") and the time specified in updates ("Time")
           may differ.

       •   Timed out values are inserted at the "tail".

       •   Explicitly flushed values are inserted at the "head".

       •   ASCII art rocks.

SSEECCUURRIITTYY CCOONNSSIIDDEERRAATTIIOONNSS
   AAuutthheennttiiccaattiioonn
       If your rrdtool installation was built without libwrap there is no form
       of authentication for clients connecting to the rrdcache daemon!

       If  your  rrdtool  installation was built with libwrap then you can use
       hosts_access  to  restrict  client  access  to  the   rrdcache   daemon
       (rrdcached).   For  more  information  on  how  to  use hosts_access to
       restrict  access  to  the  rrdcache  daemon   you   should   read   the
       hhoossttss__aacccceessss(5) man pages.

       It  is  still  highly recommended to install a packet filter or similar
       mechanism to  prevent  unauthorized  connections.  Unless  you  have  a
       dedicated VLAN or VPN for this, using network sockets is probably a bad
       idea!

   AAuutthhoorriizzaattiioonn
       There is minimal per-socket authorization.

       Authorization  is currently done on a per-socket basis. That means each
       socket has a list of commands it will accept and  it  will  accept.  It
       will   accept  only  those  commands  explicitly  listed  but  it  will
       (currently) accept these commands from anyone reaching the socket.

       If the networking sockets are to be used, it is necessary  to  restrict
       the  accepted  commands  to  those  needed by external clients. If, for
       example, external clients want to draw graphs of the cached data,  they
       should only be allowed to use the "FLUSH" command.

       Authorization  does  not  work  when  rrdcached  is socket-activated by
       systemd.

   EEnnccrryyppttiioonn
       There is no encryption.

       Again, this may be added in the future, but for the time  being  it  is
       your  job  to  keep  your  private  data  private.  Install a VPN or an
       encrypted tunnel if you statistics are confidential!

   SSaanniittyy cchheecckkiinngg
       There is no sanity checking.

       The daemon will blindly write to any file it gets told, so  you  really
       should create a separate user just for this daemon. Also it does not do
       any sanity checks, so if it gets told to write values for a time far in
       the future, your files will be messed up good!

   CCoonncclluussiioonn
       •   Security is the job of the administrator.

       •   We recommend to allow write access via UNIX domain sockets only.

       •   You have been warned.

PPRROOTTOOCCOOLL
       The  daemon communicates with clients using a line based ASCII protocol
       which is easy to read and easy to type. This makes it easy for  scripts
       to  implement  the  protocol  and  possible  for users to use telnet to
       connect to the daemon and test stuff "by hand".

       The protocol is line based, this means that each record consists of one
       or more lines. A line is terminated by the line  feed  character  0x0A,
       commonly written as "\n". In the examples below, this character will be
       written as "<LF>" ("line feed").

       After  the  connection  has been established, the client is expected to
       send a "command". A command consists of the command  keyword,  possibly
       some  arguments,  and  a  terminating  newline character. For a list of
       commands, see "Valid Commands" below.

       Example:

         FLUSH /tmp/foo.rrd<LF>

       The daemon answers with a line consisting of a status code and a  short
       status  message,  separated by one or more space characters. A negative
       status code signals an error, a positive status  code  or  zero  signal
       success.  If  the  status  code  is greater than zero, it indicates the
       number of lines that follow the status line.

       Examples:

        0 Success<LF>

        2 Two lines follow<LF>
        This is the first line<LF>
        And this is the second line<LF>

   VVaalliidd CCoommmmaannddss
       The following commands are understood by the daemon:

       FFLLUUSSHH _f_i_l_e_n_a_m_e
           Causes the daemon to put _f_i_l_e_n_a_m_e to the hheeaadd of the  update  queue
           (possibly  moving  it  there  if the node is already enqueued). The
           answer will be sent aafftteerr the node has been dequeued.

       FFLLUUSSHHAALLLL
           Causes the daemon to start flushing ALL  pending  values  to  disk.
           This  returns  immediately,  even though the writes may take a long
           time.

       PPEENNDDIINNGG _f_i_l_e_n_a_m_e
           Shows any "pending" updates for a  file,  in  order.   The  updates
           shown have not yet been written to the underlying RRD file.

       FFEETTCCHH _f_i_l_e_n_a_m_e _C_F [_s_t_a_r_t [_e_n_d] [_d_s ...]]
           Calls  "rrd_fetch"  with  the  specified  arguments and returns the
           result in text form. If necessary, the  file  is  flushed  to  disk
           first.   The   client   side  function  "rrdc_fetch"  (declared  in
           "rrd_client.h")  parses  the   output   and   behaves   just   like
           "rrd_fetch_r"  for  easy integration of remote queries.  ds defines
           the columns to dump - if none are given then all are returned

       FFEETTCCHHBBIINN _f_i_l_e_n_a_m_e _C_F [_s_t_a_r_t [_e_n_d] [_d_s ...]]
           Calls "rrd_fetch" with the  specified  arguments  and  returns  the
           result  in  text/binary  form  to  avoid unnecessary un/marshalling
           overhead.  If necessary, the file is flushed  to  disk  first.  The
           client  side  function  "rrdc_fetch"  (declared  in "rrd_client.h")
           parses the output and behaves  just  like  "rrd_fetch_r"  for  easy
           integration of remote queries.  ds defines the columns to dump - if
           none are given then all are returned

       FFOORRGGEETT _f_i_l_e_n_a_m_e
           Removes _f_i_l_e_n_a_m_e from the cache.  Any pending updates WWIILLLL BBEE LLOOSSTT.

       QQUUEEUUEE
           Shows the files that are on the output queue.  Returns zero or more
           lines  in  the  following format, where <num_vals> is the number of
           values to be written for the <file>:

               <num_vals> <file>

       HHEELLPP [_c_o_m_m_a_n_d]
           Returns a short usage message. If no command is given,  or  _c_o_m_m_a_n_d
           is  HHEELLPP,  a  list of commands supported by the daemon is returned.
           Otherwise a short description, possibly containing a pointer  to  a
           manual page, is returned.  Obviously, this is meant for interactive
           usage  and the format in which the commands and usage summaries are
           returned is not well defined.

       SSTTAATTSS
           Returns a list of metrics which can be used to measure the  daemons
           performance  and  check its status. For a description of the values
           returned, see "Performance Values" below.

           The format in which the values are  returned  is  similar  to  many
           other  line  based  protocols:  Each value is printed on a separate
           line, each consisting of the name of the value,  a  colon,  one  or
           more spaces and the actual value.

           Example:

            9 Statistics follow
            QueueLength: 0
            UpdatesReceived: 30
            FlushesReceived: 2
            UpdatesWritten: 13
            DataSetsWritten: 390
            TreeNodesNumber: 13
            TreeDepth: 4
            JournalBytes: 190
            JournalRotate: 0

       PPIINNGG
           PING-PONG,  this  is very useful when using connection pool between
           user client and RRDCACHED.

           Example:

            0 PONG

       UUPPDDAATTEE _f_i_l_e_n_a_m_e _v_a_l_u_e_s [_v_a_l_u_e_s ...]
           Adds more data to a filename. This is tthhee operation the daemon  was
           designed  for,  so  describing  the mechanism again is unnecessary.
           Read "HOW IT WORKS" above for a detailed explanation.

           Note that rrdcached only accepts absolute timestamps in the  update
           values.  Updates strings like "N:1:2:3" are automatically converted
           to  absolute  time  by  the  RRD  client  library before sending to
           rrdcached.

       WWRROOTTEE _f_i_l_e_n_a_m_e
           This command is written to the journal after a file is successfully
           written out to disk.  It is used during journal replay to determine
           which updates have already been applied.  It is _o_n_l_y valid  in  the
           journal; it is not accepted from the other command channels.

       FFIIRRSSTT _f_i_l_e_n_a_m_e [_r_r_a_n_u_m]
           Return  the  timestamp  for  the  first  CDP  in the specified RRA.
           Default is to use RRA zero if none is specified.

       LLAASSTT _f_i_l_e_n_a_m_e
           Return the timestamp for the last update to the specified RRD. Note
           that the cache is _n_o_t flushed before checking,  as  the  client  is
           expected to request this separately if it is required.

       IINNFFOO _f_i_l_e_n_a_m_e
           Return  the  configuration  information for the specified RRD. Note
           that the cache is _n_o_t flushed before checking,  as  the  client  is
           expected to request this separately if it is required.

           The information is returned, one item per line, with the format:

            I<keyname> I<type> I<value>

       CCRREEAATTEE _f_i_l_e_n_a_m_e [-s _s_t_e_p_s_i_z_e] [-b _b_e_g_i_n_t_i_m_e] [-r _s_o_u_r_c_e_f_i_l_e ...] [-t
       _t_e_m_p_l_a_t_e_f_i_l_e] [-O] _D_S_d_e_f_i_n_i_t_i_o_n_s ... _R_R_A_d_e_f_i_n_i_t_i_o_n_s ...
           This will create the RRD file according to the supplied parameters,
           provided  the  parameters are valid, and (if the -O option is given
           or if the rrdcached was started with the  -O  flag)  the  specified
           _f_i_l_e_n_a_m_e does not already exist.

       BBAATTCCHH
           This command initiates the bulk load of multiple commands.  This is
           designed  for installations with extremely high update rates, since
           it permits more than one  command  to  be  issued  per  rreeaadd(())  and
           wwrriittee(()).

           All   commands  are  executed  just  as  they  would  be  if  given
           individually, except for output to the user.   Messages  indicating
           success  are  suppressed,  and error messages are delayed until the
           client is finished.

           Command processing is finished when the client sends a dot (".") on
           its own line.  After the client has finished, the  server  responds
           with  an error count and the list of error messages (if any).  Each
           error messages indicates the number of  the  command  to  which  it
           corresponds,  and the error message itself.  The first user command
           after BBAATTCCHH is command number one.

               client:  BATCH
               server:  0 Go ahead.  End with dot '.' on its own line.
               client:  UPDATE x.rrd 1223661439:1:2:3            <--- command #1
               client:  UPDATE y.rrd 1223661440:3:4:5            <--- command #2
               client:  and so on...
               client:  .
               server:  2 Errors
               server:  1 message for command 1
               server:  12 message for command 12

       LLIISSTT [RECURSIVE] I/<path>
           This command allows to list directories and rrd databases  as  seen
           by  the  daemon.   The  root  "directory"  is the base_dir (see '-b
           dir'). When invoked with 'LIST RECURSIVE /<path>'  it  will  behave
           similarly  to 'ls -R' but limited to rrd files (listing all the rrd
           bases in the subtree of <path>, skipping empty directories).

       SSUUSSPPEENNDD _f_i_l_e_n_a_m_e
           Suspend writing to an RRD file. While  a  file  is  suspended,  all
           metrics for it are cached in memory until RREESSUUMMEE is called for that
           file or RREESSUUMMEEAALLLL is called.

       RREESSUUMMEE _f_i_l_e_n_a_m_e
           Resume  writing  to  an RRD file previously suspended by SSUUSSPPEENNDD or
           SSUUSSPPEENNDDAALLLL.

       SSUUSSPPEENNDDAALLLL
           Suspend writing to all RRD files. While a file  is  suspended,  all
           metrics for it are cached in memory until RREESSUUMMEE is called for that
           file or RREESSUUMMEEAALLLL is called.

       RREESSUUMMEEAALLLL
           Resume  writing to all RRD files previously suspended by SSUUSSPPEENNDD or
           SSUUSSPPEENNDDAALLLL.

       QQUUIITT
           Disconnect from rrdcached.

   PPeerrffoorrmmaannccee VVaalluueess
       The following counters are returned by the SSTTAATTSS command:

       QQuueeuueeLLeennggtthh _(_u_n_s_i_g_n_e_d _6_4_b_i_t _i_n_t_e_g_e_r_)
           Number of nodes currently enqueued in the update queue.

       UUppddaatteessRReecceeiivveedd _(_u_n_s_i_g_n_e_d _6_4_b_i_t _i_n_t_e_g_e_r_)
           Number of UPDATE commands received.

       FFlluusshheessRReecceeiivveedd _(_u_n_s_i_g_n_e_d _6_4_b_i_t _i_n_t_e_g_e_r_)
           Number of FLUSH commands received.

       UUppddaatteessWWrriitttteenn _(_u_n_s_i_g_n_e_d _6_4_b_i_t _i_n_t_e_g_e_r_)
           Total number of updates, i. e. calls to "rrd_update_r",  since  the
           daemon was started.

       DDaattaaSSeettssWWrriitttteenn _(_u_n_s_i_g_n_e_d _6_4_b_i_t _i_n_t_e_g_e_r_)
           Total  number  of  "data sets" written to disk since the daemon was
           started. A data set is one or more  values  passed  to  the  UUPPDDAATTEE
           command. For example: "1223661439:123:456" is one data set with two
           values.  The  term  "data set" is used to prevent confusion whether
           individual values or groups of values are counted.

       TTrreeeeNNooddeessNNuummbbeerr _(_u_n_s_i_g_n_e_d _6_4_b_i_t _i_n_t_e_g_e_r_)
           Number of nodes in the cache.

       TTrreeeeDDeepptthh _(_u_n_s_i_g_n_e_d _6_4_b_i_t _i_n_t_e_g_e_r_)
           Depth of the tree used for fast key lookup.

       JJoouurrnnaallBByytteess _(_u_n_s_i_g_n_e_d _6_4_b_i_t _i_n_t_e_g_e_r_)
           Total number of bytes written to the journal since startup.

       JJoouurrnnaallRRoottaattee _(_u_n_s_i_g_n_e_d _6_4_b_i_t _i_n_t_e_g_e_r_)
           Number of times the journal has been rotated since startup.

SSIIGGNNAALLSS
       SIGINT and SIGTERM
           The daemon exits normally on receipt of either  of  these  signals.
           Pending  updates  are  handled  in  accordance  with  the --jj and --FF
           options.

       SIGUSR1
           The daemon exits AFTER flushing all updates out to disk.  This  may
           take a while.

       SIGUSR2
           The daemon exits immediately, without flushing updates out to disk.
           Pending  updates  will be replayed from the journal when the daemon
           starts up again.  WWAARRNNIINNGG:: iiff jjoouurrnnaalliinngg ((--jj)) iiss NNOOTT  eennaabblleedd,,  aannyy
           ppeennddiinngg uuppddaatteess WWIILLLL BBEE LLOOSSTT.

BBUUGGSS
       No known bugs at the moment.

SSEEEE AALLSSOO
       rrdtool, rrdgraph

AAUUTTHHOORR
       Florian Forster <octo at verplant.org>

       Both rrrrddccaacchheedd and this manual page have been written by Florian.

CCOONNTTRRIIBBUUTTOORRSS
       kevin       brintnall       <kbrint@rufus.net>       Steve      Shipway
       <steve@steveshipway.org> Martin Sperl <rrdtool@martin.sperl.org>

1.10.3                            2026-05-25                      _R_R_D_C_A_C_H_E_D(1)
