lmdd(8)
NAME
lmdd - move io for performance and debugging tests
SYNOPSIS
lmdd [ option=value ] ...
DESCRIPTION
lmdd copies a specified input file to a specified output with possible
conversions. This program is primarily useful for timing I/O since it
prints out the timing statistics after completing.
OPTIONS
- if=name Input file is taken from name; internal is the default.
- internal is a special file that acts like Sun's
/dev/zero, i.e., it provides a buffer of zeros without
doing a system call to get them.
The following file names are taken to mean the standard input: -, 0, or stdin. - of=name Output file is taken from name; internal is the default.
- internal is a special file that acts like /dev/null,
without doing a system call to get rid of the data.
The following file names are taken to mean the standard output: -, 1, or stdout.
The following file names are taken to mean the standard error: 2, or stderr. - bs=n Input and output block size n bytes (default 8192).
- Note that this is different from dd(1), it has a 512 byte default. Also note that the block size can be followed by 'k' or 'm' to indicate kilo bytes (*1024) or megabytes (*1024*1024), respectively.
- ipat=n If n is non zero, expect a known pattern in the file
- (see opat). Mismatches will be displayed as "ERROR: off=%d want=%x got=%x". The pattern is a sequence of 4 byte integers with the first 0, second 1, and so on. The default is not to check for the pattern.
- opat=n If n is non zero, generate a known pattern on the output
- stream. Used for debugging file system correctness. The default is not to generate the pattern.
- mismatch=n If n is non zero, stop at the first mismatched value.
- Used with ipat.
- skip=n Skip n input blocks before starting copy.
- fsync=n If n is non-zero, call fsync(2) on the output file
- before exiting or printing timing statistics.
- sync=n If n is non-zero, call sync(2) before exiting or print
- ing timing statistics.
- rand=n This argument, by default off, turns on random behavior.
- The argument is not a flag, it is a size, that size is used as the upper bound for the seeks. Also note that the block size can be followed by 'k' or 'm' to indicate kilo bytes (*1024) or megabytes (*1024*1024),
- flush=n If n is non-zero and mmap(2) is available, call msync(2)
- to invalidate the output file. This flushes the file to disk so that you don't have unmount/mount. It is not as good as mount/unmount because it just flushes file pages - it misses the indirect blocks which are still cached. Not supported on all systems, compile time option.
- rusage=n If n is non-zero, print rusage statistics as well as
- timing statistics. Not supported on all systems, compile time option.
- count=n Copy only n input records.
EXAMPLES
- This is the most common usage, the intent is to measure disk performance. The disk is a spare partition mounted on /spare.
- # mount /spare
# lmdd if=internal of=/spare/XXX count=1000 fsync=1
7.81 MB in 3.78 seconds (2.0676 MB/sec) - : Flush cache
# umount /spare
# mount /spare - # lmdd if=/spare/XXX of=internal
7.81 MB in 2.83 seconds (2.7611 MB/sec)
AUTHOR
- Larry McVoy, lm@sun.com