Paul Slootman wrote:
> On Thu 02 Oct 2008, Loren M. Lang wrote:
> 
>> I currently am doing nightly backups of my server onto two USB hard
>> drives that are rotated weekly.  A nightly backup only takes 30-45
>> minutes on average, but the USB drives are left plugged in and running
>> for a full week.  The USB enclosures are usually quiet warm during the
> 
> I have a WD MyBook (the original version, when 500GB was the largest you
> could get) which spins down itself if idle for > 10 minutes. Spinup
> happens automatically upon any access, and linux doesn't seem to mind
> the short delay (I believe < 10s) while that's happening.
> 
> I've measured the power usage when spun down, and it's about 2 watts
> which I find very good.
> 
> 
> Paul Slootman
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> 
I am doing this on my two NSLU2s. Research told me that the usual USB-IDE
chips in an external enclosure do not support the ATA power down command,
so you can send it across the USB interface, but it will never get to the
actual drive.
So I opted for the solution like Paul of taking drives or enclosures that
do the power-down themselves, with some you can set the time, with others
its built-in and a fixed time.
I even have the servers booting from these disks, its all well explained
on the NSLU2 Unslung pages/wiki, and they still power down OK.

Linux does not mind about the spin-up delay in my case either, at the moment
both are Debian Etch, up till a few weeks ago one was running unslung. I
assume the techniques to get this working are the same across all distributions.

In fact I currently have one Debian that boots from a stick, logging etc.
all goes on in a RAM disk, and all the data (mp3s etc.) is on the
external hard drive. Dirvish does a backup to this drive once a day.

Cheers Brian

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