-=head1 NAME
+=head1 NAME
rrd-beginners - RRDtool Beginners' Guide
=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
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<heartbeat>. In our example, heartbeat is 600
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.
=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
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;