[kwlug-disc] powering Seagate USB external disk off and on from Linux?

[William Park]

I'm doing something similar with my BTRFS backup.

  * hdparm -y /dev/sdh  --- "standby".  It spins down but still visible,
    so system can see it and spin it up again.  There is also "sleep"
    mode (-Y) which is even lower power mode, but it disconnects and you
    can't power it up again by software.

  * sg_start --start /dev/sdh --- "start".  Also, accessing it, will
    spin it up automatically.  I don't know why sg_start --stop doesn't
    work.


On 2025-11-17 18:53, D. Hugh Redelmeier wrote:
> I want to use a cheap external HDD for backups.  I want the drive to be
> off when not in use but I don't want to be required to plug or unplug the
> drive to turn it on.
>
> Is there a way for a script to turn off a disk so it really is off enough
> and subsequently turn it on again?
>
>
> - consumer HDDs have ridiculously low power-on lifetimes, at least
>    according to their specifications
>
> - so I want my backup software to power the drive on before use and
>    off after use.
>
> - [may be relevant] Seagate external drive controllers have a flaw: to be
>    fast, you want to use UAS (USB Attached SCSI) but the controller won't
>    pass SAT commands in this mode.  You need to tell the driver that the
>    drive has a "quirk" to lock in usb-storage mode.
>    <https://www.smartmontools.org/wiki/SAT-with-UAS-Linux>
>
> Just unmounting all partitions of an HDD does not seem to cause it to spin
> down.  The drive still makes noise and is warm, even hours later.
>
> Turning off the drive, using Gnome's Disks or (untested) udisksctl(1),
> does stop the drive.  But I don't know how to subsequently turn it on via
> a program.  For example, Gnome Disks doesn't see the drive once it has
> been turned off.  The way I know to turn on the drive is to physically
> unplug the USB cable and plug it in again.
>
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