Re: HDD power up in standby

[Janos Haar]

Hello,

----- Original Message ----- 
From: "Robert Hancock" <hancockrwd@xxxxxxxxx>
To: "Janos Haar" <djani22@xxxxxxxxxxxx>
Cc: <linux-kernel@xxxxxxxxxxxxxxx>
Sent: Tuesday, December 15, 2009 2:02 AM
Subject: Re: HDD power up in standby


> On 12/14/2009 04:22 AM, Janos Haar wrote:
> > Hello list,
> >
> > I have posted to the common, because this theme is for more lists (ide,
> > sata, scsi), i think....
> >
> > I know you will not like me guys, but i have one wish.... :-)
> >
> > I am building cheap but big storages, and after 12 drive / PC i have 
> > faced
> > with one problem:
> > The too much spinup current wich made by the 12-16 drive at the same 
> > time.
> > In my actual case, in 12V, there is more than 2A / drive for some 
> > seconds.
> >
> > I know, in SCSI, there is a jumper for this, and the card can wake up the
> > drives one by one, but i am using 2TB drives, and in SCSI/SAS this have
> > horrible price...
> > I have done some invesrtigation, and found this:
> > The most of the simple sata drives handles the PUIS mode (by set
> > features ata command), but unfortunately
> > only the professional and expensive raid cards supports the wakeing up.
> > If the cheap cards founds only 0 byte drives, this is not a problem at 
> > all,
> > because linux usually not use BIOS support fortunately. :-)
> > But i have found when i have spent a little time in google, and in the
> > documentation, linux doesn't support PUIS.
> >
> > I think this would be great, and (relatively) simple to implement this
> > feature.
> > I can imagine in this way:
> > Wake up from PUIS is disabled by default, but can be enabled by command
> > line
> > parameter, or compile time configuration.
> > The drivers should send the wake up command one by one to the drives, 
> > waits
> > for RDY DSC, and than scan the drives, and register....
> >
> > What do you think?
>
> As far as I can see, if the drive reports it's in power-up in standby mode 
> from the identify response, the kernel will send the command to spin up 
> the drive. It might depend on whether parallel scan is enabled for the 
> controller as far as whether they actually spin up one at a time, however.

I am working with 2TB Hitachi drive wich is set to PUIS, and reports itself 
as 0 byte, but existing device (pcb factory alias), but with my promise 
card, the kernel see only bad geometry and disable the port only. :-(
I have missed something?

> > (Now i am searching for the solution to send the wakeup command by user
> > program, and than do a "hotplug" in software only, but this is not an
> > "elegant" solution...)
> >
> >
> > Best Regards,
> > Janos Haar

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