* Overview

NMONMerge was written as a preprocessor to merge and optionally
consolidate NMON data files prior to using the data in other tools.

* Installation

NMONMerge.rb is a simple Ruby script. It requires only a base Ruby
interpreter.

* Operation

Call NMONMerge.rb with one or more NMON data files as arguments, and
redirect the output to a new file.

Files will be processed in order, and the results sent to STDOUT.

** Merging

Given multiple NMON data files, NMONMerge will combine the data
samples from files in the order specified as arguments. The data
samples will be reorganized along a common timeline, with updated time
interval indexes.

*** Merging Example

A common method for running NMON is to launch it daily from cron,
writing out samples throughout the day to a data file. Each day a new
file is created.

Unfortunately, each file has a timeline with a time interval index
beginning at T0 and incrementing along the sample interval.

Multiple files have duplicate time indexes, preventing concatenation
from combining the files in a useful fashion.

NMONMerge reindexes the data along a merged common timeline when used
with multiple files. Now, a week's worth of files containing a single
day's data can be combined into a weekly file for analysis.

** Consolidation

When merging multiple NMON files the total number of data samples can
become unwieldy, overwhelming other performance tools with limited
input buffers.

*** Consolidation Example

By using the consolidation option, NMONMerge skips records while
preserving the new output timeline. 

The argument to the consolidation option is an integer specifying the
ratio of records to skip. A simple modulo is performed, keeping one
record in X, where X is the consolidation parameter. 

Using a parameter of 10, only one data sample in ten is preserved in
the output. Using a value of 1 is equivalent to 1 in 1 records, or no
consolidation.

* Links

 - NMON

   http://www-941.ibm.com/collaboration/wiki/display/WikiPtype/nmon

 - NMON Analyzer

   http://www-941.ibm.com/collaboration/wiki/display/WikiPtype/nmonanalyser

 - NMON Consolidator

   http://www-941.haw.ibm.com/collaboration/wiki/display/WikiPtype/nmonconsolidator