You 'll be prompt to press [Enter] to stop led:

# diag -d hdisk0  -T "identifyRemove -a identify"

Turning off diagnostic lights (LED) on a power server, or partition

# /usr/lpp/diagnostics/bin/usysfault -s normal 

List LED status on LPAR, all components, and on a single disk

[root@viotsth5]/home/padmin# /usr/lpp/diagnostics/bin/usysfault
normal
[root@viotsth5]/home/padmin# /usr/lpp/diagnostics/bin/usysfault -t
U8286.42A.21343CW
U78CD.001.FZH8729-P1
U78CD.001.FZH8729-P1-C4
U78CD.001.FZH8729-P1-C5
U78CD.001.FZH8729-P1-C6
U5887.001.G5A902G
U5887.001.G5A902G-P1-D13
U5887.001.G5A902G-P1-D14
U5887.001.G5A902G-P1-D15
U5887.001.G5A902G-P1-D16
U5887.001.G5A902G-P1-D17
U5887.001.G5A902G-P1-D18
U5887.001.G5A902G-P1-C1
U5887.001.G5A902G-P1-C2
[root@viotsth5]/home/padmin# /usr/lpp/diagnostics/bin/usysident -d hdisk1
normal

Change LED status on hdisk1

[root@viotsth5]/home/padmin# /usr/lpp/diagnostics/bin/usysident -s identify -d hdisk1
[root@viotsth5]/home/padmin# /usr/lpp/diagnostics/bin/usysident -d hdisk1
identify
[root@viotsth5]/home/padmin# /usr/lpp/diagnostics/bin/usysident -s normal -d hdisk1
[root@viotsth5]/home/padmin# /usr/lpp/diagnostics/bin/usysident -d hdisk1
normal

Install (download) the microcode

# diag -d fcs0 -T download

Description about: “M”, “L”, “C”, “P” when choosing the microcode:

  "M" is the most recent level of microcode found on the source.
  It is later than the level of microcode currently installed on the adapter.  
                                           
  "L" identifies levels of microcode that are later than the level of microcode currently installed on the adapter.
  Multiple later images are listed in descending order.                

  "C" identifies the level of microcode currently installed on the adapter.                        
                                               
  "P" identifies levels of microcode that are previous to the level of microcode currently installed on the adapter.
  Multiple previous images are listed in the descending order. 

List firmware level

# lsmcode -A 

To Back level the firmware

# diag -d fcsX -T "download -f -l previous"

Install (download) the microcode

# /usr/lpp/diagnostics/bin/usysident ? 
    usage: usysident [-s {normal | identify}] 
                     [-l location code | -d device name]
           usysident [-t] 

To check the LED status of the system:

# /usr/lpp/diagnostics/bin/usysident 
normal 

To check the LED status of /dev/hdisk1:

# /usr/lpp/diagnostics/bin/usysident -d hdisk1 
normal

To activate the LED of /dev/hdisk1:

# /usr/lpp/diagnostics/bin/usysident -s identify -d hdisk1 
# /usr/lpp/diagnostics/bin/usysident -d hdisk1 
identify

To turn of the LED again of /dev/hdisk1:

# /usr/lpp/diagnostics/bin/usysident -s normal -d hdisk1 
# /usr/lpp/diagnostics/bin/usysident -d hdisk1 
normal