iozone benchmark doc. You may use one or more of the following keywords [iozone msword pdf ozone] to. IOzone. IOzone is a file system benchmark utility. Originally made by William Norcott, SCO OpenServer, Solaris, Mac OS X, Windows (95/98/Me/NT/2K/XP). I wrote this book using Microsoft Word 98 for the Macintosh. Hence, the screen shots, menus, etc. might look a little different if you are using a different version or .
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Iozone —Rac This tells Iozone to include the close in the measurement.
Examples of running Iozone: This test is writing a new file so again the overhead of the metadata is included in the measurement. See —q for setting maximum record size. The following are some graphs that were generated from the Iozone output files. Iozone will generate an Excel compatible report to standard out.
In general you should be able to see three or four plateaus. This test measures the performance of reading a file backwards. This tells the operating system that all the data in the mmap space needs to be written to disk synchronously. When the -Q option is used Iozone will generate four. Iozone has been ported to many machines and runs under many operating systems.
If the size of the spot is small enough to fit in the CPU data cache then the performance is very high. This is due to the fact that the buffer cache is now completely full of dirty data that must be written before the buffer can be reused. This is a classic example of tuning for a specific application. Future processes or threads will be placed on the next processor.
What is “iozone”
Additional notes on how to make the graphs Iozone sends Excel compatible output to standard out. This test is only available in throughput mode. This is generally sufficient but for some very large systems you may need to use the —g option to increase the maximum file size. When testing with unmount between tests it is necessary for the temporary file under test to be in a directory that ioozone be unmounted. When running throughput tests this option allows the user to specify the least number of processes or threads to start.
The performance of a system under this type of activity can be impacted by several factors iozkne as: This test measures the performance of reading a file using the library function fread.
Don Capps wnorcott us. This may be redirected to a file mwword then processed with Excel. This file may be imported with Microsoft Excel space delimited and used to create a graph of the filesystem performance. This iozohe handy if an application wishes to treat files as chunks of memory.
The number of names should be equal to the number of processes or threads that are specified. The fields are space delimited.
CPU cache effect Buffer cache effect Not measured The graph above shows single stream performance where file size and request size are changed. This flag allows one to turn off mzword stonewalling and see what happens.
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The normal output for Iozone as well as the Excel portion are in the same output stream. It is not possible to unmount ioozne current working directory as the process Iozone is running in this directory.
During the throughput tests all threads or processes are forced to a barrier before beginning the test. The reason that this occurs when the file is bigger than the buffer cache is because the write to the first block on the rewrite case will not find the block in the buffer cache and will be forced to clean a mswofd before using it. Most operating systems do not detect this behavior or implement any techniques to enhance the performance under this type of access behavior.
This is useful for finding if certain offsets have very high latencies. This is because the writes are going into the buffer cache and the application is allowed to continue immediately. Iiozone files mwsord be imported into Excel and then graphed. One can see from the data the impacts of the extent allocations for extent based filesystems with this option.
Not all platforms scale so well. This is useful only if you suspect that close is broken in the operating system currently under test. This run was taken with the —a option. The —A option tells Msworc that you are willing to wait and want dense coverage for small transfers even when the file size is very large. The second field is iozine path, on the client, for the working directory where Iozone will execute.
One may also specify -s k size in Kbytes or -s m size in Mbytes or -s g size in Gbytes. You may see another plateau if the platform has a primary and secondary processor caches.