FIO is a tool for measuring IO performance. You can use FIO to run a user-defined workload and collect the associated performance data.

A good writeup can be found at Fio Basics. For more information, do MAN on fio

Step 1: To Install fio, make sure you activated the epel repository.

# yum install fio

Parameters to be used.

% fio --filename=myfio --size=5GB --direct=1 --rw=randrw --bs=4k --ioengine=libaio --iodepth=256 --runtime=120 --numjobs=4 --time_based --group_reporting --name=iops-test-job --eta-newline=1

• –filename
  An entire block size or filename can be specified. For example if you are testing block size filename=/dev/sda:/dev/sdb
• –size
  Indicate the size of the test file generated.  If you are testing the block size and did not specify the size, the entire block will be used.
• –direct=1
  This means that the page cache is bypassed. No memory is used.
• –rw
  Check whether IO is access sequentially or randonly. There are a few options.
  read – Sequential reading
  write – Sequential Write
  randread – random reading
  randwrite – random writing
  readwrite , rw – Mixed, sequential workload
  randrw – Mixed Random Workload
• –bs
  Block Size. By default 4kB is used.
• –ioengine=libiao
  libaio  enables asynchronous access from the application level. The option would requires –direct=1
  
• –iodepth
  Refers to how many requests.
• –numjobs
  Specifies the number of processes that start the jobs in parallel
• –runtime
  Terminate processing after the specified period of time
• –name
  Name of the job
• –time-based
  fio will run for the duration of the runtime specified
• –group_reporting
  Display statistics for groups of jobs as a whole instead of for each individual job. This is especially true if
  numjobs is used;