Measuring NFS traffic with DTrace

Below you can find simple script written in DTrace which will show you in a given time intervals what is a distribution of data written and read to/from NFS mounted filesystems in Mb per second (average in the interval). It will be updated continuously every given amount of time.

Script expects four arguments: low high step interval. First two of them are low and high of a range in Mbs you want your output, step describes resolution of the output and interval is a resolution of a measurement (time interval from which Mbs is calculated). In an example below I wanted to see output in a range 50-150Mbs with 5Mbs step calculated for intervals of 10s and see results every 10s. As you can see most of the time I have on average 90-120Mbs generated to/from NFS servers.
Note that this is only an estimate.

bash-3.00# cat io-nfs-throughput.d
#!/usr/sbin/dtrace -qs

BEGIN
{
  bsum = 0;
}

io:nfs::start
{
  bsum += args[0]->b_bcount;
}

tick-$4
{
  @a["Mbs"] = lquantize(bsum*8/($4*1024*1024),$1,$2,$3);
  printa(@a);
  bsum=0;
}

bash-3.00# ./io-nfs-throughput.d 50 150 5 10s
[...] after some time
  Mbs
           value  ------------- Distribution ------------- count
              55 |                                         0
              60 |                                         1
              65 |                                         2
              70 |                                         2
              75 |@                                        3
              80 |@                                        8
              85 |@@@                                      17
              90 |@@@@@                                    32
              95 |@@@                                      16
             100 |@@@@                                     23
             105 |@@@@                                     22
             110 |@@@@                                     21
             115 |@@@@                                     21
             120 |@@@                                      19
             125 |@@@                                      17
             130 |@@                                       14
             135 |@@                                       11
             140 |@                                        7
             145 |                                         0
          >= 150 |@                                        4