# iotop
Traceback (most recent call last):
  File "/usr/bin/iotop", line 16, in 
    main()
  File "/usr/lib/pymodules/python2.6/iotop/ui.py", line 506, in main
    locale.setlocale(locale.LC_ALL, '')
  File "/usr/lib/python2.6/locale.py", line 513, in setlocale
    return _setlocale(category, locale)
locale.Error: unsupported locale setting

Solution:

# export LCC_ALL=C

for making it permanent, You have to add it to .bashrc

reference:
http://www.quantumwise.com/support/faq/103-localeerror-unsupported-locale-setting?catid=24%3Aerror-messages