Spike Killer for Cacti Graphs version 1.1

The spike killer for Cacti Graphs is a newly designed spike killer that, although
designed to be used with Cacti, does not require Cacti to operate.  If was inspired
by the original spike killer perl script written by Vins Vilaplana but is an all
new design, and written in PHP (my favorite scripting language).

This new spike killer chooses two alternate spike kill methodologies that are
different Vins original work.  In addition to removing spikes, it provides
reports of the contents of your RRDfiles.

The spike killing methodologies supported in this utility are as follows:

  - Remove via Standard Deviation
  - Remove via Variance from Average

The Standard Deviation method first calculates the average of all Data Sources and
RRA's and determines the Standard Deviation of each combination.  It will then
remove any sample over X Standard Deviations from the Average.  The utility has the
option of replacing the spike by the average, or by a NaN at your discretion.

The Variance Method first calculates the average of all Data Sources and RRA's.
Before doing that it removes the top X and bottom X samples from each sample set
treating them as outliers.  Then, based upon the revised average will remove
all spikes Y percent above or below the revised averages.  Again, like the
Standard Deviation method, you have the option of replacing the spike with the
revised average or a NaN.

For those using a web application to remove spikes, you have the ability to
format output messages for HTML.

The utility also supports a Dryrun option that will only conduct analysis of the
RRDfiles and report how many spikes using each methodology would have been removed.

NOTE: The utility does not currently make a backup copy of the RRDfile, and may
not work with HW predict.  So, please use cautiously.

When you run the utility using the "--help" option, you will receive the following
output:

Cacti Spike Remover v1.0, Copyright 2009, The Cacti Group, Inc.

Usage:
removespikes.php -R|--rrdfile=rrdfile [-M|--method=stddev] [-A|--avgnan] [-S|--stddev=N]
                 [-P|--percent=N] [-N|--number=N] [-D|--dryrun] [-d|--debug]
                 [--backup] [--html] [-h|--help|-v|-V|--version]

The RRDfile input parameter is mandatory.  If no other input parameters are specified the defaults
are taken from the Spikekill Plugin settings.

-M|--method      - The spike removal method to use.  Options are 'stddev'|'variance'
-A|--avgnan      - The spike replacement method to use.  Options are 'avg'|'nan'
-S|--stddev      - The number of standard deviations +/- allowed
-P|--percent     - The sample to sample percentage variation allowed
-N|--number      - The maximum number of spikes to remove from the RRDfile
-D|--dryrun      - If specified, the RRDfile will not be changed.  Instead a summary of
                   changes that would have been performed will be issued.
--backup         - Backup the original RRDfile to preserve prior values.

The remainder of arguments are informational
--html           - Format the output for a web browser.
-d|--debug       - Display verbose output during execution
-v -V --version  - Display this help message
-h --help        - display this help message

Suggestions, Patches or Improvements to: thewitness@cacti.net.  Enjoy!!