disk performance benchmark tool
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README

IOMELT - Rodrigo Albani de Campos (camposr<at>gmail<dot>com)

* What is iomelt?
IOMELT is a benchmark tool for storage devices. 
It is designed to be simple to use and understand.
Currently it runs only on Linux and Mac OS X.

* How do I build IOMELT?
It should be simple as:

	% make

* Why build yet another benchmark tool?
I needed something simpler, easier to understand and - more important -  easier to explain
than currently available tools.

* What are the main goals of this project?
	1. Provide consistent and reproducible results
	2. Keep code simple and well documented so that any can understand how it works

* How does iomelt works?
It runs a series of five sequential tests:

	1. Serial Write test
	2. Serial Read test
	3. Random Rewrite test
	4. Random Reread test
	5. Random Mixed Read/Write test

* What are the current options?
As of November 2012, version 0.7 supports the following command line options:

	-b BYTES	Block size used for IO functions (must be a power of two)
	-d 		Dump data in a format that can be digested by pattern processing commands
	-D 		Print time in seconds since epoch
	-h 		Prints usage parameters
	-H 		Omit header row when dumping data
	-n 		Do NOT convert bytes to human readable format
	-o 		Do NOT display results (does not override -d)
	-O 		Reopen worload file before every test
	-p PATH 	Directory where the test file should be created
	-r 		Randomize workload file name
	-R 		Try to enable Direct IO
	-s BYTES	Workload file size (default: 10Mb)
	-v 		Controls the level of verbosity
	-V 		Displays version number

Block size and File size (-b and -s options) are in bytes(default), Kilobytes ('K' suffix), Megabytes ('M' suffix), or Gigabytes ('G' suffix).
Unless specified, block size value is the optimal block transfer size for the file system as returned by statvfs


* How can I use it?
Typically you can use it on the command line and it will output its results in a human
readable format.
You can configure it as a cron job and use the '-d' option so you can create time series charts or
scatter plots with the results.

* Why it only works on Linux and Mac OS X?
Mostly because the system calls that try to disable buffer caching are not portable. 

* I have an awesome idea and would like to help!
Send me an e-mail at camposr<at>gmail<dot>com

------- VERSION HISTORY ---------

- 0.4
	Added -p option to specify the path
	Added the mixed read/write test
	Simplified the random seed generator
	Code cleanup
	Check for return codes for read and write operations

- 0.5
	Added the parseFileSize function that parses the '-s' and '-b' command line options to allow the unit suffixes
	Makefile now has a 'install' target
- 0.5.1
	Added a man page
	Added a version number to the printHelp() output
	Units may be specified in lower case characters
	OS X support (port by Gleicon Moraes, thanks!)

- 0.6 (August 2012)
	Data dump now includes file and block size
	Introduced the -H command line option

- 0.7 (November 2012)
	* The block size has no fixed value anymore, instead it uses statvfs() to retrieve the optimal value for the underlying file system.
	* IOMelt now supports Direct IO (-R option).
	* In order to support Direct IO (O_DIRECT) the buffer is created using posix_memalign() instead of malloc().
	* There's a new option (-O) that will cause IOMelt to reopen the workload file before each test.
	* All tests source code were moved to a file called io.c
	* Diagnostic, error and debugging information are now printed using the myWarn() function defined in the verbose.c file.
	* getUsage(), startUsage() and resetUsage() are not used anymore and were replaced for a much cleaner interface.
	* All lseek() calls now are wrapped into a function called mySeek(), the seek position now is always a multiple of the block size.