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 Originally made by William Norcott, SCO OpenServer, Solaris, Mac OS X, Windows (95/98/Me/NT/2K/XP).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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These are read offset latency, write offset latency, rewrite offset latency oizone reread offset latency. If you don’t see at least 3 plateaus then you probably have the maximum file size set too small. Iozone will allocate another internal buffer that is aligned to the same processor cache boundary and is of a size that matches the processor cache. When testing with unmount between tests it is necessary for the temporary file under test to be in a directory that can be unmounted.

This may be needed if the client is running NFS version 3. The graph above was created by running Iozone multiple times and then graphing the combination of the results. Read at offset zero for a length of 4 Kbytes, then seek Kbytes, and then read for a length of 4 Kbytes, then seek Kbytes and so on.

Future processes or threads will be placed on the next processor. An example would be if the file size is just a bit bigger than the buffer cache size. The second field is the path, on the client, for the working directory where Iozone will execute. While the database users are happy, the other users may not be so happy as the entire system may be giving all of the system resources to the database users at the expense of all other users.

The third field is the path, on the client, for the executable Iozone. Others have an array of buffers.


Another type of graph that can be produced is the Latency graph. Just copy Iozone to wherever you wish to test the filesystem performance and then run it. This test measures the performance of writing and re-writing a particular spot within a file. Stonewalling in throughput tests to eliminate straggler effects. The first sub process or thread will begin on the specified processor.

An example would be to have an array in memory that is also being maintained as a file in the files system.

This test measures the performance of reading a file that was recently read. Before you mswodr Iozone please read the run rules at the bottom of this document. The 3D graphs are column oriented. In this mode every byte is validated. When the next dialog box pops up you need to select “Columns”. For file sizes less than the size of the processor cache oizone can see the rise in performance as well.

During the throughput tests all threads or processes are forced to a barrier before beginning the test. 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. Iozone has been ported to many machines and runs mxword many operating systems.


One might consider using it before your company purchases its next platform. This is where the request size fits in the processor cache. Although interesting to see, it is unlikely that you will be able to get applications to never write files that are bigger than the processor cache However it might be possible to get applications to try to re-use buffers and keep the buffer size smaller than the processor cache size.

The users may discover that the machine is very slow when running this new application and become dissatisfied with the decision to purchase this platform. If you don’t know how big the buffer cache is, or if it is a dynamic buffer cache then just set the maximum file size to be greater than the total physical memory that is in the platform.


Source code availability Iozone is available for free. After that the rest should be straight forward. Normally Iozone omits testing of small record sizes for very large files when used in full automatic mode. This test is only available in throughput mode. When both the file size and the transfer size is less than the processor cache it rises even higher.

What is “iozone”

iozond An example of this type of enhancement is: See —y for setting minimum record size. Some applications read into a single buffer over and over. The semantics of mmap files is somewhat different than normal files.

The number of names should be equal to the number of processes or threads that are specified. This test is writing to an existing file so the performance should be higher as there are no metadata operations required. The file contains triplets of information: It is normal for the performance to be higher as the operating system generally maintains a cache of the data for files that were recently read.

So to get the graphs one needs to scroll down to the Excel portion of the file and graph the data in that section.

This test measures the performance of reading a file using the library function fread. This again is a typical application behavior for applications that have data structures contained within a file and is accessing a particular region of the data structure.

There are several sets of graph data. Produces output that covers all tested file operations for record sizes of 4k mword 16M for file sizes of 64k to M.