Re: Can't get drives containing spare devices to spindown

["Marc L. de Bruin" <marc@debruin.org>]

Neil Brown wrote:

>On Thursday June 22, marc@debruin.org wrote:
>  
>
>>Marc L. de Bruin wrote:
>>
>>    
>>
>>>Situation: /dev/md0, type raid1, containing 2 active devices 
>>>(/dev/hda1 and /dev/hdc1) and 2 spare devices (/dev/hde1 and /dev/hdg1).
>>>
>>>Those two spare 'partitions' are the only partitions on those disks 
>>>and therefore I'd like to spin down those disks using hdparm for 
>>>obvious reasons (noise, heat). Specifically, 'hdparm -S <value> 
>>><device>' sets the standby (spindown) timeout for a drive; the value 
>>>is used by the drive to determine how long to wait (with no disk 
>>>activity) before turning off the spindle motor to save power.
>>>
>>>However, it turns out that md actually sort-of prevents those spare 
>>>disks to spindown. I can get them off for about 3 to 4 seconds, after 
>>>which they immediately spin up again. Removing the spare devices from 
>>>/dev/md0 (mdadm /dev/md0 --remove /dev/hd[eg]1) actually solves this, 
>>>but I have no intention actually removing those devices.
>>>
>>>How can I make sure that I'm actually able to spin down those two 
>>>spare drives?
>>>      
>>>
>
>This is fixed in current -mm kernels and the fix should be in 2.6.18.
>
>NeilBrown
>  
>
Thanks Neil for your quick reply. Would it be possible to elaborate a 
bit on the problem and the solution? I guess I won't be on 2.6.18 for 
some time...

Marc.