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 Originally made by William Norcott, SCO OpenServer, Solaris, Mac OS X, Windows (95/98/Me/NT/2K/XP).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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For example if your system has 1 Gbyte of memory then you would want to try something like: This will purge the processor cache and allow one to see the memory subsystem without the acceleration due to the processor cache.

Iozone will create latency versus offset data files that can be imported with a graphics package and plotted.

The semantics of mmap files is somewhat different than normal files. Anomaly 1 There is also a dropoff for file sizes of 8 MB and larger.

Iozone —a If you wish to generate graphs then you may wish to turn on Excel mode. This option should be used in conjunction with the -u option. There is no need to have any install procedures as IOzone creates all of its files in the current working directory. The simplest way to get started is to try the automatic mode. This file may be imported with Mswotd Excel space delimited and used to create a graph of the filesystem performance.

The reason that this occurs when the file is bigger than the buffer cache is because the write to msworrd first block on the rewrite case will not find the iozonne in the buffer cache and will be forced to clean a buffer before using it.


When importing the file be sure to tell Excel to import with “delimited” and then click msworx, then click on the “space delimited” button.

The —a option will automatically stop using transfer sizes less than 64k once the file size is 32 MB or larger. This test measures the performance of reading and writing a file with accesses being made to random locations within the file.

Once they are all ready to start then they are all released at the same time. In the re-read mswword graph one can clearly see the client side cache that is in NFS Version 3. This is where the request size fits in the processor cache.

This test measures the performance of reading a file using the library function fread. It is normal for the rewrite performance to be higher than the performance of writing a new file. This flag allows one to turn off the stonewalling and see what happens.

This test measures the performance of reading a file backwards. This test measures the performance of writing and re-writing a particular spot within a file.

An example would be: These are read offset latency, write offset latency, rewrite offset latency and reread offset latency.

What does iozone mean – Definition of iozone – Word finder

If you don’t see at least 3 plateaus then you probably have the maximum file size set too small. Also note that the processor cache effects can be seen for file sizes of 16 Kbytes to 1Mbyte.

By using Iozone to get a broad filesystem performance coverage the buyer is much more likely to see any hot or cold spots and pick a platform and operating system that is more well balanced. This test is writing to an existing file so the performance should be higher as there are no metadata operations required. Excel importable output for graph generation. This access behavior can also sometimes produce interesting performance anomalies. Here one can see that there are some file sizes and some record sizes that have very bad performance.


This should result in higher performance as the operating system is likely to have the file data in cache. The —A option tells Iozone that you are willing to wait and want dense coverage for small transfers even when the file size is very large.


This may seem like a strange way to read a file but in fact there are applications that do this. When a file is written that already exists the work required is less as the metadata already exists. Iozone will default to a maximum file size of Mbytes.

This tells the operating system that all the data in the mmap iozons needs to be written to disk synchronously.

The performance of a system under this type of activity can be impacted by several factors such as: This is used internally to help speed up the test. Normally this is not a desirable area to test because it is very time consuming to write a MB file in 4k transfer sizes.

What is “iozone”

One might consider using ioxone before your company purchases its next platform. Iozone will unmount and remount this mount point before beginning each test. Examples of running Iozone: 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.