SAS HDD Activity LED always on - Ready LED Meaning bit

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fzabkar
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SAS HDD Activity LED always on - Ready LED Meaning bit

Postby fzabkar » Sat Apr 20, 2013 11:16 pm

SAS HDD Activity LED always on - Ready LED Meaning bit

Some Seagate SAS HDD models and/or firmware configure the activity LED so that it indicates READY rather than BUSY.

According to Table 305 in Section 4.3.17.3.2. of the following document, the behaviour of the Ready LED is determined by the "Ready LED Meaning" bit (RLM) in SCSI code page 19h.

SCSI Commands Reference Manual:
http://www.seagate.com/staticfiles/supp ... 93068c.pdf

Section 12.5.1 of the ST3300657SS product manual defines the behaviour of the LED when the Ready LED Meaning bit is a 0 and also when it is a 1.

Cheetah 15K.7 SAS Product Manual, Rev. D:
http://www.seagate.com/staticfiles/supp ... 16226d.pdf

When the bit is a 0 and the drive is spun up, the LED is ON whenever the drive is inactive, and OFF whenever it is active. Conversely, if the bit is a 1 and the drive is spun up, then the LED is OFF whenever the drive is inactive, and ON whenever it is active. Simply stated, the LED behaves like a READY indicator when the RLM bit is 0, and like a BUSY indicator when the RLM bit is 1.

Therefore, should the user desire that the activity LED indicate when the drive is BUSY rather than READY, the solution is to set the Ready LED Meaning bit to 1 in mode page 19h.

sdparm is a Linux utility that can "access SCSI modes pages; read VPD pages; send simple SCSI commands". It has also been ported to Windows.

sdparm(8) - Linux man page:
http://linux.die.net/man/8/sdparm

The sdparm utility (including downloads):
http://sg.danny.cz/sg/sdparm.html

The procedure is as follows:

Code: Select all

 open a DOS command prompt in Windows
 
 sdparm --wscan                        lists recognized drives, eg PD2 and PD4

 sdparm --get=RLM DEVICE PD2           gets the current value of RLM, in this case 0

 sdparm --set=RLM --save DEVICE PD2    sets RLM = 1


Note that, even if the changes are successful, the behaviour of the Ready LED may not change until the processor re-examines the RLM bit, which may not be until the next power cycle. Therefore the user may not notice an immediate change in LED behaviour straight after executing sdparm.

Here are two threads where users have applied the above procedure:

http://forums.seagate.com/t5/Savvio-Che ... m-p/129744
http://forums.seagate.com/t5/Savvio-Che ... 33120#M646

FrancisDouglas
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Re: SAS HDD Activity LED always on - Ready LED Meaning bit

Postby FrancisDouglas » Sun Sep 15, 2013 6:26 pm

fzabkar wrote:SAS HDD Activity LED always on - Ready LED Meaning bit

Some Seagate SAS HDD models and/or firmware configure the activity LED so that it indicates READY rather than BUSY.

According to Table 305 in Section 4.3.17.3.2. of the following document, the behaviour of the Ready LED is determined by the "Ready LED Meaning" bit (RLM) in SCSI code page 19h.

SCSI Commands Reference Manual:
http://www.seagate.com/staticfiles/supp ... 93068c.pdf

Section 12.5.1 of the ST3300657SS product manual defines the behaviour of the LED when the Ready LED Meaning bit is a 0 and also when it is a 1.

Cheetah 15K.7 SAS Product Manual, Rev. D:
http://www.seagate.com/staticfiles/supp ... 16226d.pdf

When the bit is a 0 and the drive is spun up, the LED is ON whenever the drive is inactive, and OFF whenever it is active. Conversely, if the bit is a 1 and the drive is spun up, then the LED is OFF whenever the drive is inactive, and ON whenever it is active. Simply stated, the LED behaves like a READY indicator when the RLM bit is 0, and like a BUSY indicator when the RLM bit is 1.

Therefore, should the user desire that the activity LED indicate when the drive is BUSY rather than READY, the solution is to set the Ready LED Meaning bit to 1 in mode page 19h.

sdparm is a Linux utility that can "access SCSI modes pages; read VPD pages; send simple SCSI commands". It has also been ported to Windows.

sdparm(8) - Linux man page:
http://linux.die.net/man/8/sdparm

The sdparm utility (including downloads):
http://sg.danny.cz/sg/sdparm.html

The procedure is as follows:

Code: Select all

 open a DOS command prompt in Windows
 
 sdparm --wscan                        lists recognized drives, eg PD2 and PD4

 sdparm --get=RLM DEVICE PD2           gets the current value of RLM, in this case 0

 sdparm --set=RLM --save DEVICE PD2    sets RLM = 1


Note that, even if the changes are successful, the behaviour of the Ready LED may not change until the processor re-examines the RLM bit, which may not be until the next power cycle. Therefore the user may not notice an immediate change in LED behaviour straight after executing sdparm.

Here are two threads where users have applied the above procedure:

http://forums.seagate.com/t5/Savvio-Che ... m-p/129744
http://forums.seagate.com/t5/Savvio-Che ... 33120#M646

Thanks for sharing this very useful information.. I am just using the device and the details will help me lot..Thanks again

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Re: SAS HDD Activity LED always on - Ready LED Meaning bit

Postby Spildit » Sun Nov 10, 2013 3:55 pm

Thanks for sharing !
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