Welland Greenstar HDD spindown problem

[tjrundy]

Hello,

Apologies for a 2nd email, but I thought that by splitting out topics
into threads, it might be easier for people to refer to these in the
future.

I'm running Unslung 6.10 beta. I have two hard drives, one natively
formatted on port 2, and a 1TB FAT 32 formatted drive on port 1
(Samsung HD103UJ). The Enclosure for port 1 is a Welland Greenstar:
http://www.welland.com.tw/html/green/740pss.html.

I got it since it was recommended on the wiki:
http://www.nslu2-linux.org/wiki/FAQ/SpinDownUSBHarddisks#method2

The Enclosure has 4 power states:

1. On - Read / Write normal RPM
2. Idle - reduced RPM
3. Spindown
4. 'Power Off'

It would appear that this power off actually turns the power to the
disc off in such a way that it disconnects the disc from the USB. When
it's connected to an XP machine and the disc is accessed when in this
'Power Off' mode it makes the sound of a USB device disconnected and
then reconnected, before you can access the files.

When connected to the NSLU2, at boot it mounts it as /dev/sdb and
HDD_1_1_1. When the drive is subsequently accessed and it's in this
'Power Off' state, it then mounts it as /dev/sdc and HDD_1_2_1. If the
drive powers off again, next time it will appear as /dev/sdd and
HDD_1_3_1, and so on.

Unfortunately there's no way to set the enclosure to spindown but
never 'power-off'.

Please does anyone know how I can force subsequent mounts to use the
same device and HDD_1_1_1?

Many thanks,

Tom.

[clowenst]

On Sun, Jul 13, 2008 at 2:01 PM, tjrundy <tjrundy@...> wrote:

> Hello,
>
> Apologies for a 2nd email, but I thought that by splitting out topics
> into threads, it might be easier for people to refer to these in the
> future.
>
> I'm running Unslung 6.10 beta. I have two hard drives, one natively
> formatted on port 2, and a 1TB FAT 32 formatted drive on port 1
> (Samsung HD103UJ). The Enclosure for port 1 is a Welland Greenstar:
> http://www.welland.com.tw/html/green/740pss.html.
>
> I got it since it was recommended on the wiki:
> http://www.nslu2-linux.org/wiki/FAQ/SpinDownUSBHarddisks#method2
>
> The Enclosure has 4 power states:
>
> 1. On - Read / Write normal RPM
> 2. Idle - reduced RPM
> 3. Spindown
> 4. 'Power Off'

I find state 2 really hard to believe.  Disk drives aren't built that
way.  The heads fly dynamically on a thin layer of air, and the drive
platters must be running at full speed for this to happen.  Otherwise
you get a head crash, which is not good for the head, the platter, or
the data.

    carl
--
carl lowenstein
marine physical lab, u.c. san diego
clowenstein@...

[Rod Whitby-2]

Carl Lowenstein wrote:

> On Sun, Jul 13, 2008 at 2:01 PM, tjrundy <tjrundy@...> wrote:
>> The Enclosure has 4 power states:
>>
>> 1. On - Read / Write normal RPM
>> 2. Idle - reduced RPM
>> 3. Spindown
>> 4. 'Power Off'
>
> I find state 2 really hard to believe.  Disk drives aren't built that
> way.  The heads fly dynamically on a thin layer of air, and the drive
> platters must be running at full speed for this to happen.  Otherwise
> you get a head crash, which is not good for the head, the platter, or
> the data.

See the conclusion paragraph at
http://www.tomshardware.com/reviews/wd-caviar-gp,1703-8.html

"The main feature in WD's GreenPower portfolio is the dynamic adjustment
of the drive's spindle speed. It can run at speeds between 5,400 RPM and
7,200 RPM to save energy whenever high performance isn't needed."

Dunno about what the enclosure in question can do, but the latest
GreenPower WD drives apparently can reduce the RPM of the spindles to
save power.

-- Rod