X-Git-Url: https://git.octo.it/?p=rrdtool.git;a=blobdiff_plain;f=doc%2Frrdcached.pod;h=8ed29794707bcd4fbaf34320731032fb5dbcbb8e;hp=7631351b4d6fcda136d753b566938f1079160331;hb=e1597899f28b7fed13a029c84d9b36bbe5f16505;hpb=a12627275ff8487174cbb907a066f62a00b6ae44 diff --git a/doc/rrdcached.pod b/doc/rrdcached.pod index 7631351..8ed2979 100644 --- a/doc/rrdcached.pod +++ b/doc/rrdcached.pod @@ -6,7 +6,7 @@ rrdcached - Data caching daemon for rrdtool =head1 SYNOPSIS -B [B<-l> I
] [B<-w> I] [B<-z> I] [B<-f> I] [B<-j> I] +B [B<-l> I
] [B<-w> I] [B<-z> I] [B<-f> I] [B<-j> I] [-F] =head1 DESCRIPTION @@ -34,6 +34,21 @@ socket. If I
begins with C, everything following that prefix is interpreted as the path to a UNIX domain socket. Otherwise the address or node name are resolved using L. +For network sockets, a port may be specified by using the form +CI
B<]:>I>. If the address is an IPv4 address or a fully +qualified domain name (i.Ee. the address contains at least one dot +(C<.>)), the square brackets can be omitted, resulting in the (simpler) +CB<:>I> pattern.. The default port is B<42217/udp>. + +The following formats are accepted. Please note that the address of the UNIX +domain socket B start with a slash in the second case! + + unix: + / + + []: + : + If the B<-l> option is not specified the default address, C, will be used. @@ -72,7 +87,20 @@ 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 B<-f>. On clean shutdown, the journal files are removed. +given by B<-f>. + +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 B<-F> option. + +=item B<-F> + +ALWAYS flush all updates to the RRD data files when the daemon is shut +down, regardless of journal setting. =item B<-b> I @@ -128,6 +156,15 @@ the disk itself. All other commands can send a B 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. +=head1 ERROR REPORTING + +The daemon reports errors in one of two ways: During startup, error messages +are printed to C. One of the steps when starting up is to fork to the +background and closing C - 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 L. The facility used it +C. + =head1 HOW IT WORKS When receiving an update, B does not write to disk but looks for an @@ -163,9 +200,8 @@ The downside of caching values is that they won't show up in graphs generated from the RRDEfiles. To get around this, the daemon provides the "flush command" to flush specific files. This means that the file is inserted at the B of the update queue or moved there if it is already enqueued. The flush -command will return after the update thread has dequeued the file, so there is -a good chance that the file has been updated by the time the client receives -the response from the daemon, but there is no guarantee. +command will return only after the file's pending updates have been written +to disk. +------+ +------+ +------+ ! head ! ! root ! ! tail ! @@ -293,6 +329,11 @@ Causes the daemon to put I to the B of the update queue (possibly moving it there if the node is already enqueued). The answer will be sent B the node has been dequeued. +=item B + +Causes the daemon to start flushing ALL pending values to disk. This +returns immediately, even though the writes may take a long time. + =item B [I] Returns a short usage message. If no command is given, or I is @@ -387,6 +428,39 @@ Number of times the journal has been rotated since startup. =back +=head1 SIGNALS + +=over 4 + +=item SIGINT and SIGTERM + +The daemon exits normally on receipt of either of these signals. Pending +updates are handled in accordance with the B<-j> and B<-F> options. + +=item SIGUSR1 + +The daemon exits AFTER flushing all updates out to disk. This may take a +while. + +=item 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. B. + +=back + +=head1 SIGNALS + +=over 4 + +=item SIGINT and SIGTERM + +The daemon exits normally on receipt of either of these signals. + +=back + =head1 BUGS No known bugs at the moment.