servicing them.

              w_await
                     The average time (in milliseconds) for write requests issued to the device to be served. This includes the time spent by the requests in queue and the time spent servicing them.

              d_await
                     The average time (in milliseconds) for discard requests issued to the device to be served. This includes the time spent by the requests in queue and the time spent servicing them.

              f_await
                     The average time (in milliseconds) for flush requests issued to the device to be served.  The block layer combines flush requests and executes at most one at a time.  Thus flush operations could be twice
                     as long: Wait for current flush request, then execute it, then wait for the next one.

              aqu-sz The average queue length of the requests that were issued to the device.
                     Note: In previous versions, this field was known as avgqu-sz.

              %util  Percentage of elapsed time during which I/O requests were issued to the device (bandwidth utilization for the device). Device saturation occurs when this value is close to 100% for  devices  serving  re‐
                     quests serially.  But for devices serving requests in parallel, such as RAID arrays and modern SSDs, this number does not reflect their performance limits.

OPTIONS
       -c     Display the CPU utilization report.

       --compact
              Don’t break the Device Utilization Report into sub-reports so that all the metrics get displayed on a single line.

       -d     Display the device utilization report.

       --dec={ 0 | 1 | 2 }
              Specify the number of decimal places to use (0 to 2, default value is 2).

       -f directory
       +f directory
              Specify  an  alternative  directory  for iostat to read devices statistics. Option -f tells iostat to use only the files located in the alternative directory, whereas option +f tells it to use both the standard
              kernel files and the files located in the alternative directory to read device statistics.

              directory is a directory containing files with statistics for devices managed in userspace.  It may contain:

              - a "diskstats" file whose format is compliant with that located in "/proc",
              - statistics for individual devices contained in files whose format is compliant with that of files located in "/sys".

              In particular, the following files located in directory may be used by iostat:

              directory/block/device/stat
              directory/block/device/partition/stat

              partition files must have an entry in directory/dev/block/ directory, e.g.:

              directory/dev/block/major:minor --> ../../block/device/partition

       -g group_name { device [...] | ALL }
              Display statistics for a group of devices.  The iostat command reports statistics for each individual device in the list then a line of global statistics for the group displayed as group_name and made up of all
              the devices in the list. The ALL keyword means that all the block devices defined by the system shall be included in the group.

       -H     This option must be used with option -g and indicates that only global statistics for the group are to be displayed, and not statistics for individual devices in the group.

       -h     This option is equivalent to specifying --human --pretty.

       --human
              Print sizes in human readable format (e.g. 1.0k, 1.2M, etc.)  The units displayed with this option supersede any other default units (e.g.  kilobytes, sectors...) associated with the metrics.

       -j { ID | LABEL | PATH | UUID | ... } [ device [...] | ALL ]
              Display persistent device names. Keywords ID, LABEL, etc. specify the type of the persistent name. These keywords are not limited, only prerequisite is that directory with