Oliver (or anybody else):

Adding dynamic (AKA runtime) power management to the SCSI core is
looking a little difficult.  (Actually, since as far as I know the SCSI
specification takes no heed of power management, perhaps this should be
called "idle-device management".)

Imagine a SCSI disk has been idle long enough that we want to spin it
down.  When I/O requests do start to arrive later on, we want to delay
them in the request queue until the disk has a chance to spin back up.  
Or even to fail them, if the user has done a "manual" suspend.

These are conflicting requirements.  How can we send the START-STOP 
UNIT commands to spin the disk up/down through the request queue while 
delaying or failing all others?  What happens if one of the 
START-STOP UNIT commands encounters a problem and the error handler 
needs to send some commands of its own?

Any suggestions or ideas are welcome.

Alan Stern

-
To unsubscribe from this list: send the line "unsubscribe linux-scsi" in
the body of a message to [EMAIL PROTECTED]
More majordomo info at  http://vger.kernel.org/majordomo-info.html

Reply via email to