
USB drives with no phantom load - edward
http://joeyh.name/blog/entry/usb_drives_with_no_phantom_load/
======
jws
I share the author’s concerns for off grid power use. 3 watts per drive (I
assume a wall wart for a 3.5” drive) works out to 72watt hours per day. About
1/10th of a $200 solar panel. Double or triple that to cover batteries and
electronics. Then you run into discontinuities in system sizing where you
can’t easily add just one more panel. Conserving energy suddenly makes a lot
of sense.

USB hubs with per port power control are the flying unicorn of hardware. Once
in a while some vendor slips up and makes one, but by the time people figure
it out the vendor has ended the model or replaced it with a different model
under the same model number. It’s especially frustrating because many of the
USB hub chipsets support the feature, but only if the manufacturer puts a
switching transistor on each port. It literally would only cost pennies per
port to have the feature.

~~~
AgalmicVentures
Yepkit [1] makes these! They have 3 port hubs for USB 2 and 3, as well as
single port "hubs" \-- all controlled through a simple command-line interface
or Python API. They also have other good stuff like USB controlled relay
boards and upstream USB hubs to switch devices between hosts.

I've used their products in a variety of automation projects for clients and
at home, and have only good things to say.

[1] [https://www.yepkit.com/](https://www.yepkit.com/)

~~~
haldean
Where were you two months ago when I desperately needed this for a project?!
Thank you so much, this is awesome.

------
Abishek_Muthian
Tangentially, I'm curious on how OP monitors health of USB drives.

Getting SMART data from USB drives has been a pain on linux as the kernel
rejects SAT ATA pass-through commands & so doesn't work with smartmontools[1].

I have tested across different USB 3.0 drives such as Seagate Backup Plus,
MYDIGITALSSD|OTG, SAMSUNG Portable SSD T5 all of which use 'uas' driver under
linux & if used with USB 3.0 hub like Tplink USB 3.0 port hub; it bridges
using 'hub/4p' driver.

After trying out several other methods in vain, the only tool which I found to
be helpful in checking for USB drive health on linux is discscan[2]; which
tests for unreadable sectors & latency without using SMART values.

[1]:
[https://www.smartmontools.org/wiki/USB](https://www.smartmontools.org/wiki/USB)

[2]: [https://github.com/baruch/diskscan](https://github.com/baruch/diskscan)

~~~
Vogtinator
I have never any issues with USB HDDs with smartctl.

In the rare cases where autodetection did not work, smartctl -d <type> with
trial and error works.

~~~
Abishek_Muthian
I see, I forgot to mention - d scsi gives only basic manufacturer info and
tests fail.

Does your drive work in uas mode?

------
zokier
3 W per drive when shut down seems like huge amount. For reference, Raspberry
Pi 3B+ consumes about 2 W when idle, and 2B 2.5 W under load.

[https://www.pidramble.com/wiki/benchmarks/power-
consumption](https://www.pidramble.com/wiki/benchmarks/power-consumption)

------
comboy
It's cool but I don't know if I would want additional latency (especially in
the case where they are currently going to sleep) plus possibility of turning
them off at the wrong moment to save $0.2 per month.

~~~
Someone
Why do you think this is about cost? The article says _”I 've not had any
network attached storage at home, because it's offgrid”_, so I think it’s
about preventing the house from powering down.

~~~
pronoiac
I can't find a concise page to link, but he has a house that's off-the-grid,
using solar panels and batteries. So he pays attention to power consumption.

~~~
bcaa7f3a8bbc
Link this page.
[https://lwn.net/Articles/672352/](https://lwn.net/Articles/672352/)

~~~
lkj
Thank you! The following quote resonates heavily with my mind:

> I'm fairly addicted to that point in development of a project where it's all
> about exploring a vast solution space, and making countless little choices
> that will hopefully add up to something coherent and well thought out and
> useful. Or might fail gloriously.

