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Appendix A: Benchmarks and test tools
The IOzone benchmark was used to measure sequential read and write throughput (MB/sec) as well as
random read and write I/O operations per second (IOPS).
The mdtest benchmark was used to test metadata operation performance.
The checkstream utility was used to test for data correctness under failure and failover cases.
The Linux dd utility was used for initial failover testing and to measure data throughput as well as the
time to complete file copy operations.
A.1. IOzone
You can download IOzone from http://www.iozone.org/. Version 3.408 was used for these tests and
installed on both the NFS servers and all the compute nodes.
The IOzone tests were run from 1-64 nodes in clustered mode. All tests were N-to-N, that is N clients
would read or write N independent files.
Between tests, the following procedure was followed to minimize cache effects:
 Unmount NFS share on clients.
 Stop the cluster service on the server. This unmounts the XFS file system on the server.
 Start the cluster service on the server.
 Mount NFS Share on clients.
The following table describes the IOzone command line arguments.
Appendix A — IOzone command line arguments Table 8.
IOzone Argument
Description
-i 0
Write test.
-i 1
Read test.
-i 2
Random Access test.
-+n
No retest.
-c
Includes close in the timing calculations.
-t
Number of threads.
-e
Includes flush in the timing calculations.
-r
Records size.