[geeks] SATA Drives and Delay Start

[Jochen Kunz]

On Wed, 05 Mar 2008 21:01:43 -0600 (CST)
Lionel Peterson <lionel4287 at verizon.net> wrote:

> Which I read as meaning the drive need to support it, and the computer
> needs to act a certain way. It appears that this is a two-part
> process, the drive knows to lok for a certain condition before
> spinning up, and the BIOS exerts a control signal once it is up and
> running. Again, the model in my mind would be a line held in a certain
> state that does not occur by default (high?), and is brought low by by
> the controller in a prescribed manner if a certain option enabled in
> the firmware. In this canse the firmware overrides the default nature
> of the hardware.
I understand it this way: Originaly pin 11 on the SATA power connector
was GND. Machines that don't suport staggered spinup have GND on that
pin. This causes the drive to spin up immediately. If the PSU / SATA
backplane support staggered spinup pin 11 is open. (Respectively an
activity LED is connected to pin 11.) The drive detects the open pin and
does not spin up. Now the controller needs to issue a spin up command.
In case of a normal mainboard SATA controller the mainboard BIOS must
issue the spin up command. If it doesn't you got no disk.

You can think of it as the "delay startup" jumper, knowen from SCSI
drives, moved to the power connector.
--


tsch|_,
       Jochen

Homepage: http://www.unixag-kl.fh-kl.de/~jkunz/