spinning down external disk

[David A. Bandel]

On Thu, Mar 3, 2011 at 09:57, Jorge Almeida <jjalmeida at gmail.com> wrote:
> How do you do it?

Usually done through acpi(d) which can monitor, shutdown devices
(usually fan control, etc.).

>
> I have external disks used to backups. They are turned on only for the
> needed time, usually, so power consumption and noise are not the
> issue. The problem is whether turning off the power switch is bad for
> the hardware. I can spin down one of the disks through software
> (unbinding the device from the controlling driver, the enclosure has
> USB conection). This amounts to desconnecting the usb cable manually.
> Other disk will just keep happilly spinning... I suppose it depends on
> the enclosure.

not so much the enclosure as the disk or disk controller.  sounds to
me like the only way to stop the second hard disk is shutting off the
power.

>
> Question is: turning off the power will have the same effect as using
> sofware, or is it more aggressive?

You should make sure the disks are unmounted first.  If so, and we're
talking USB (hotplug type hardware), then powering down should make no
difference -- again, if the disks are unmounted first.

>
> And anyone knows other approaches?

That's about it.  Looks like you're into hardware approaches if
software won't work (those telnet power strips you can kill power to
remotely).

Ciao,

David A. Bandel
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