mdt(1) mdt(1)
NAME
mdt - Metadata performance test
SYNOPSIS
mdt [options] path [path...]
DESCRIPTION
mdt is a utility that can be used to measure the relative metadata per-
formance of a given file system(s). By default, mdt measures cre-
ates/second and removes/second. Optionally mdt will also measure the
per second rates for stat, chmod, and move (rename) operations.
Each path specified on the command line corresponds to a mount point
for a file system to be tested. By default, mdt will start 8 pthreads.
Each pthread will make a directory and create 16384 files in the direc-
tory. The number of pthreads (direectories) can be specified via the
-n option, and the number of file per directory can be specified via
the -f option.
mdt is a metadata only test and no writes or reads are done. By de-
fault files are zero length. For a StorNext file system, space may be
allocated to the file via the -b option which performs a StorNext API
CvApi_VerifyAlloc call. Be aware that allocating space to files in
this manner is not reflected in the file size.
On completion, mdt will print the number of files and rates for the
specified metadata requests in the form of operations/second. The -v
option will expand output listing per stream detail.
Unless the -R option is specified, mdt will remove all created files
and directories in the remove test section.
For StorNext file systems, mdt will unmount and then mount the target
file systems between test sections in order to clear the client metada-
ta cache. Targeted file systems should not be busy as to prevent re-
mounting. The -U option will cause mdt to bypass remounting between
test sections.
OPTIONS
-? Display usage.
-a Run all test sections. In addition to create and remove, rates
for stat, chmod, move (rename) are also measured.
-b prealloc_size_in_bytes
Specify the size in bytes to preallocate after creating a file.
The default is 0 bytes and no preallocate.
Optionally, a single letter suffix can represent bytes in units.
mdt single letter unit suffixes are as follows.
k KB 10^3 1,000
m MB 10^6 1,000,000
b GB 10^9 1,000,000,000
K KiB 2^10 1,024
M MiB 2^20 1,048,576
B GiB 2^30 1,073,741,824
-C Do not create files. This option requires that a create run was
done at some previous time and the files were not removed. See
the -R option.
-c Run the chmod test section.
-d[dd] Run in debug mode. The more "d's" specified, the more debug in-
formation is printed.
-E csv_file
Create and write results to the specified .csv file. A .csv
file, (comma separated value) is a file that can be consumed by
a spreadsheet application like Microsoft Excel.
-e csv_file
Write results to the specified .csv file; one that can be read
by Microsoft Excel or other spreadsheet application. Data is ap-
pended to the specified csv file which must exist. See the -E
option.
-f number_of_files
Specify the number of files per directory. Optionally a single
letter suffix can be provided. See the -b option for suffix de-
tail.
-F fsname
Specify the name of the file system to use on the remount. The
file system name returned by the mount command varies by operat-
ing system. If you have trouble with remounts, you may have to
specify the file system name.
-m Run the move/rename test section. Files are renamed in within
their parent directories.
-n number_of_directories
The specified number of directories are created. Each will con-
tain the number of files specified by the -f option. A pthread
is created for each directory to execute the designated opera-
tions.
-R Skip the remove section and leave the files in place.
-s Run the stat test section. This section will execute readdir
operations and stat each file in each directory; the equivalent
of an ls -l command.
-T tag_string
Write the specified tag string to the standard output and to the
csv file if the option to write a csv file is selected. This
can be used to stamp results with a name identifying a given
test scenario.
-U Do not unmount and remount the file system between test sec-
tions.
-v Print verbose output. The result for each stream is reported.
-V Print the mdt version information and exit.
EXAMPLES
Run the create and remove test sections on a single file system:
per1-# mdt /jhb10
mdt: Timing metadata ops/second on 8 streams of 16384 files on 1 file system(s)
mount point #files creates removes
/jhb10 131072 18441 23792
Run the create and remove test sections on four file systems:
per1-# mdt /jhb10 /jhb11 /jhb12 /jhb13
mdt: Timing metadata ops/second on 8 streams of 16384 files on 4 file system(s)
mount point #files creates removes
/jhb10 131072 13818 12134
/jhb11 131072 13772 11821
/jhb12 131072 13839 12117
/jhb13 131072 13726 12098
mdt: Aggregate: 524288 54901 47283
Run all test sections on four file systems:
per1-# mdt -a /jhb10 /jhb11 /jhb12 /jhb13
mdt: Timing metadata ops/second on 8 streams of 16384 files on 4 file system(s)
mount point #files creates stats chmods moves removes
/jhb10 131072 14105 32904 16721 8366 12072
/jhb11 131072 14135 32912 16616 8375 11969
/jhb12 131072 14175 32883 16659 8436 11895
/jhb13 131072 14003 33917 17092 8411 12131
mdt: Aggregate: 524288 56005 131510 66462 33465 47578
Run the create and remove test sections on four file systems. Create
32 directories using 32 threads with 8192 files in each.
per1-# mdt -f8K -n32 /jhb10 /jhb11 /jhb12 /jhb13
mdt: Timing metadata ops/second on 32 streams of 8192 files on 4 file system(s)
mount point #files creates removes
/jhb10 262144 12149 10683
/jhb11 262144 12292 10730
/jhb12 262144 11859 10780
/jhb13 262144 11782 10806
mdt: Aggregate: 1048576 47123 42732
NOTES
The number of files (-f) and directories (-n) are per file system.
The number of pthreads (streams) that are run in each file systems cor-
responds to the number of directories specified.
Other than #files, the output values represent metadata operations/sec-
ond.
FILES
/System/Library/Filesystems/acfs.fs/Contents/bin/mdt
SEE ALSO
cvfs(8)
StorNext File System June 2015 mdt(1)
Mac OS X 10.12.3 - Generated Sat Feb 4 18:11:22 CST 2017