Iostat

iostat is a program that shows how many I/O operations happen in a specified timeframe.

Install it

To install iostat, install the package sysstat. For example with SUSE Linux 11.3 you open a console and enter:

yast -i sysstat

Run it

Just call IOstat plus the time interval in seconds:

# iostat 10
Linux 2.6.34.7-0.5-desktop (tweedleburg)        12/11/10        _x86_64_        (8 CPU)

avg-cpu:  %user   %nice %system %iowait  %steal   %idle
           0.67    0.00    0.17    0.07    0.00   99.09

Device:            tps   Blk_read/s   Blk_wrtn/s   Blk_read   Blk_wrtn
sdb               1.35         5.76        28.55    1387011    6870465
sda               1.35         5.56        28.55    1337701    6870465
md126             4.26        11.32        28.38    2723674    6830024

You will get a new block every 10 seconds in this case.