Subject: Re: powerhooks and SCSI disks
To: Michael Lorenz <>
From: Jason Thorpe <>
List: tech-kern
Date: 12/16/2005 09:05:53
On Dec 16, 2005, at 7:44 AM, Michael Lorenz wrote:

> I'm currently looking for ways to improve power management on
> SPARCbooks, mainly adding things like some sort of standby mode,  
> turning
> off unused peripherals and so on. We can for instance turn off  
> power for
> the internl SCSI disk ( in case a drive wouldn't honour a motor stop
> command ) So, I have a few questions:

What drive would not honor a STOP command?  Seems broken... anyway...

> - are there any objections against adding a power hook to sd so it  
> would
>   flush the drive's cache before we're going to remove power?

This seems like a fine thing to do.

> - is there anything to do after turning the drive back on to resume
>   operation?

I can't think of anything special.

One thing you might want to make sure of is that our SCSI I/O path  
can handle the case where a command fails BECAUSE the drive is not  
spinning, and can recover by issuing a START command to the drive.

-- thorpej