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BONNIE(1)		FreeBSD	General	Commands Manual		     BONNIE(1)

     bonnie -- Performance Test	of Filesystem I/O

     bonnie [-d	scratch-dir] [-s size-in-MB] [-m machine-label]

     Bonnie tests the speed of file I/O	from standard C	library	calls.	It
     reads and writes 8KB blocks to find the maximum sustained data rate (usu-
     ally limited by the drive or controller) and additionally rewrites	the
     file (better simulating normal operating conditions and quite dependent
     on	drive and OS optimisations).

     The per character read and	write tests are	generally limited by CPU speed
     only on current generation	hardware. It takes some	35 SPECint92 to	read
     or	write a	file at	a rate of 1MB/s	using getc() and putc().

     The seek test results depend on the buffer	cache size, since the fraction
     of	disk blocks that fits into the buffer cache will be found without any
     disk operation and	will contribute	zero seek time samples.	 (See BUGS be-

     -d	scratch-dir
	     Specify the directory where the test file gets written. The de-
	     fault is the current directory. Make sure there is	sufficient
	     free space	available on the partition this	directory resides in.

     -s	size-in-MB
	     Specify the size of the test file in MByte. This much space must
	     be	available for the tests	to complete.

     -m	machine-label
	     Specify a label to	be written in the first	column of the result

     iozone(1),	iostat(8)

     Bonnie was	written	by Tim Bray <>.

     Bonnie tries hard to measure disk performance and not the quality of the
     buffer cache implementation. In merged buffer caches common today,	the
     buffer cache size is often	only limited by	total RAM on an	otherwise un-
     loaded system. Be sure to use a file at least twice at large as available
     RAM to protect against artificially high results.

     There is no way to	keep the buffer	cache from increasing the reported
     seek rate.	This is	because	the fraction of	accesses corresponding to the
     amount of the file	cached,	will be	done without seeks.  If	your buffer
     cache is half the size of the file	used, then half	the requests will be
     satisfied immediately, and	and the	seek rate printed will be twice	the
     actual value.

UNIX				 May 18, 1995				  UNIX


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