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by pedrocr 4598 days ago
Isn't spin down controlled by the host and not the drive?
2 comments
cnvogel 4598 days ago
The host can spin down a drive manually, but most often it's done autonomously be the drive.

‣  In Linux you can manually ...

• check the power state of your drive using: hdparm -C /dev/sda

• manually spin down the drive (standby) using: hdparm -y /dev/sda (it will immediately spin up at the first attempt to read a sector)

‣  Or you configure the automatic standby of the drive (which also does not involve the OS)...

• hdparm -S n /dev/sda will configure the timeout of the drive to a value encoding the time to spin-down on a non-linear scale, check the manpage

• hdparm -B n /dev/sda will configure another type of power management which doesn't specify a fixed timeout, but rather a vendor-defined type of arbitrary power saving measures on a scale of 1..254 (1: waste power, 254: conserve power, n>128 allows spin down)

The latter two options are handled internally by the drive and (as far as I know) even stored non-volatile.

http://linux.die.net/man/8/hdparm

(Edit: fixed my broken English ;-) )

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Filligree 4598 days ago
So, actually you got -B backwards. n < 128 allows spin-down.
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jzwinck 4598 days ago
Some drives like WD's Green series have variable RPM to save power (and therefore heat). I don't think the OS is involved at all with controlling how fast those disks spin (so long as they are spinning at all).
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nknighthb 4598 days ago
WD's marketroids tried very hard to give people that impression, but it's false.

http://www.wdc.com/wdproducts/library/SpecSheet/ENG/2879-771...

At the very bottom, in small, grey text, you'll find "IntelliPower" defined as:

"A fine-tuned balance of spin speed, transfer rate and caching algorithms designed to deliver both significant power savings and solid performance. For each WD Green drive model, WD may use a different, invariable RPM."

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