How to check 3.5" HDD LEDs under Linux

1. Download & Install the tool sg_ses from the following commands by different OS:

# yum install sg3_utils - Fedora/RedHat/Centos

# apt-get install sg3_utils -Ubuntu/Debian

2. Enter the following command to confirm enclosure name of the controller card

# lsscsi -g

3. LED modes:

Blink Activity (BLUE) and Fault LED (RED):

# sg_ses --index=<HDD index> --set=locate /dev/sgx
or
# sg_ses --index=<HDD index> --set=ident /dev/sgx

Example: # sg_ses --index=0 --set=locate dev/sg0

Stop blinking Activity (BLUE) and Fault LED (RED):

# sg_ses --index=<HDD index> --clear=locate /dev/sgx
or
# sg_ses --index=<HDD index> --clear=ident /dev/sgx

Example: # sg_ses --index=0 --clear=locate dev/sg0

Light on the Fault LED (RED) and Off the Activity LED (BLUE):

# sg_ses --index=<HDD index> --set=fault /dev/sgx

Example: # sg_ses --index=0 --set=fault /dev/sg0

Light on the Activity LED (BLUE) and Off the Fault LED (RED):

# sg_ses --index=<HDD index> --clear=fault /dev/sgx

Example: # sg_ses --index=0 --clear=fault /dev/sg0

Note: HDD Index Reference: