IBM REDP-4285-00 User Manual
4285ch02.fm
Draft Document for Review May 4, 2007 11:35 am
72
Linux Performance and Tuning Guidelines
make see
: Finally after a minimum of three runs the results can be viewed using the make
see command. The results will be displayed and can be copied to a spreadsheet
application for further analysis or graphical representation of the data.
application for further analysis or graphical representation of the data.
2.4.2 IOzone
IOzone is a file system benchmark that can be utilized to simulate a wide variety of different
disk access patterns. Since the configuration possibilities of IOzone are very detailed it is
possible to simulate a targeted workload profile very precisely. In essence IOzone writes one
or multiple files of variable size using variable block sizes.
disk access patterns. Since the configuration possibilities of IOzone are very detailed it is
possible to simulate a targeted workload profile very precisely. In essence IOzone writes one
or multiple files of variable size using variable block sizes.
While IOzone offers a very comfortable automatic benchmarking mode it is usually more
efficient to define the workload characteristic such as file size, I/O size and access pattern. If
a file system has to be evaluated for a database workload it would be sensible to cause
IOzone to create a random access pattern to a rather large file at large block sizes instead of
streaming a large file with a small block size. Some of the most important options for IOzone
are:
efficient to define the workload characteristic such as file size, I/O size and access pattern. If
a file system has to be evaluated for a database workload it would be sensible to cause
IOzone to create a random access pattern to a rather large file at large block sizes instead of
streaming a large file with a small block size. Some of the most important options for IOzone
are:
-b <output.xls>
Tells IOzone to store the results in a Microsoft® Excel® compatible
spreadsheet
spreadsheet
-C
Displays output for each child process (can be used to check if all
children really run simultaneously)
children really run simultaneously)
-f <filename>
Can be used to tell IOzone where to write the data
-i <number of test>
This option is used to specify what test are to be run. You will always
have to specify -i 0 in order to write the test file for the first time.
Useful tests are -i 1 for streaming reads and -i 2 for random read and
random write access as well as -i 8 for a workload with mixed random
access
have to specify -i 0 in order to write the test file for the first time.
Useful tests are -i 1 for streaming reads and -i 2 for random read and
random write access as well as -i 8 for a workload with mixed random
access
-h
Displays the onscreen help
-r
Tells IOzone what record or I/O size that should be used for the tests.
The record size should be as close as possible to the record size that
will be used by the targeted workload
The record size should be as close as possible to the record size that
will be used by the targeted workload
-k <number of async I/Os>
Uses the async I/O feature of kernel 2.6 that often is used by
databases such as IBM DB2®
databases such as IBM DB2®
-m
Should the targeted application use multiple internal buffers then this
behavior can be simulated using the -m flag
behavior can be simulated using the -m flag
-s <size in KB>
Specifies the file size for the benchmark. For asynchronous file
systems (the default mounting option for most file systems) IOzone
should be used with a file size of at least twice the systems memory in
order to really measure disk performance. The size can also be
specified in MB or GB using m or g respectively directly after the file
size.
systems (the default mounting option for most file systems) IOzone
should be used with a file size of at least twice the systems memory in
order to really measure disk performance. The size can also be
specified in MB or GB using m or g respectively directly after the file
size.
-+u
Is an experimental switch that can be used to measure the processor
utilization during the test
utilization during the test