So I've scoured the boards for more information about hdparm, but I haven't quite found anything like my problem.
My intention is to reduce the power consumption/current draw on my embedded setup; I am basically doing initial tests by measuring the current from the power supply and checking the changes as i let the drive idle or if I issue a forced standby/sleep command.
Drive Specs: http://wdc.custhelp.com/cgi-bin/wdc....p?p_faqid=1410
*I've also tested this on a Seagate laptop drive
5V power supply
Without a HD attached, I get about ~600 mA on my board
With a drive in Idle I'm probably around ~840 mA
If i issue a hdparm -y /dev/sda , I get about 770 mA
I check my status with hdparm -C /dev/sda it says it's in "standby" mode
If I wake the drive and I try to issue a -Y (sleep) command, I see no performance gain: ~770 mA
So according to the drive spec, a device in sleep should only be an additional 30 mA and standby would be 50 mA. Meaning I should see a total current draw of around 630 or 650 mA; I can only assume the drive is only getting as low as power mode 3 which is still 170 mA. That makes sense since I jump from 600 mA to 770 mA.
Anyone know if laptop drives do not read ATA commands correctly? I have the same problem on 2 different WD drives and a seagate drive. While the disc feels like it stops spinning at Standby/sleep commands, there has to be a reason why i'm still wasting 170 mA in "sleep" mode. If someone could shed some light on my situation it would be very much appreciated. Thanks in advance.