X-Git-Url: https://git.octo.it/?a=blobdiff_plain;f=doc%2Frrd-beginners.pod;h=5ac79973f6d728864867c30dedb3f53289667cfe;hb=bec44cf332e54de7860ea693a2b5b441cf4da7d2;hp=37145e65f171cca2ae980db7057809c1ece6ff5a;hpb=7f4b880d9d5c7a48e273f52e8dfa54fae39006e3;p=rrdtool.git diff --git a/doc/rrd-beginners.pod b/doc/rrd-beginners.pod index 37145e6..5ac7997 100644 --- a/doc/rrd-beginners.pod +++ b/doc/rrd-beginners.pod @@ -1,4 +1,4 @@ -=head1 NAME +=head1 NAME rrd-beginners - RRDtool Beginners' Guide @@ -58,8 +58,8 @@ data flow to update the RRDtool database. =back RRDtool is designed to store time series of data. With every data -update, an assosiated time stamp is stored. Time is always expressed -in seconds passed since epoch (01-01-1971). RRDtool can be installed +update, an associated time stamp is stored. Time is always expressed +in seconds passed since epoch (01-01-1970). RRDtool can be installed on Unix as well as Windows. It comes with a command set to carry out various operations on RRD databases. This command set can be accessed from the command line, as well as from Shell or Perl scripts. The @@ -135,9 +135,9 @@ explained better with the following example: Values = 300, 600, 900, 1200 Step = 300 seconds - COUNTER DS = 1, 1, 1, 1 + COUNTER DS = 1, 1, 1, 1 DERIVE DS = 1, 1, 1, 1 - ABSOLUTE DS = 1, 2, 3, 4 + ABSOLUTE DS = 1, 2, 3, 4 GAUGE DS = 300, 600, 900, 1200 The next parameter is B. In our example, heartbeat is 600 @@ -149,7 +149,7 @@ is much better than to assume a missing value was 0 (zero) or any other number which might also be a valid data value. For example, the traffic flow counter on a router keeps increasing. Lets say, a value is missed for an interval and 0 is stored instead of UNKNOWN. Now when -hte next value becomes available, it will calculate the difference +the next value becomes available, it will calculate the difference between the current value and the previous value (0) which is not correct. So, inserting the value UNKNOWN makes much more sense here. @@ -251,7 +251,7 @@ generation is done using Perl scripts. These scripts are shown below: =head3 Perl script (retrieves data from database and generates graphs and statistics) #!/usr/bin/perl -w - # This script fetches data from target.rrd, creates a graph of memory + # This script fetches data from target.rrd, creates a graph of memory # consumption on the target (Dual P3 Processor 1 GHz, 656 MB RAM) # call the RRD perl module @@ -262,8 +262,8 @@ generation is done using Perl scripts. These scripts are shown below: my $start_time = $end_time - 2592000; # set start 30 days in the past # fetch average values from the RRD database between start and end time - my ($start,$step,$ds_names,$data) = - RRDs::fetch("target.rrd", "AVERAGE", + my ($start,$step,$ds_names,$data) = + RRDs::fetch("target.rrd", "AVERAGE", "-r", "600", "-s", "$start_time", "-e", "$end_time"); # save fetched values in a 2-dimensional array my $rows = 0;