Unplugging the power from a Raspberry Pi?

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raboof
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Unplugging the power from a Raspberry Pi?

Postby raboof » Sun Feb 08, 2015 2:08 pm

For an on-stage/on-the-road device, you want to be able to unplug the power from the device whenever you feel like it. That is of course different from how you usually treat a linux computer.

Does anyone have experience with that? Do you choose a filesystem technology that is especially resilient? Or perhaps try to mount the filesystem in read-only mode entirely?

ash
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Re: Unplugging the power from a Raspberry Pi?

Postby ash » Sat Jun 13, 2015 6:57 pm

Disconnecting the power at any random moment isn't healthy for your pi.
It only takes a few seconds to shut down anyway.
Also, it's no big deal to run the pi from batteries.
Hope this helps!

If you are interested -

Power switch:

https://www.raspberrypi.org/forums/view ... 40&t=48757

or

https://www.pi-supply.com/product/pi-su ... er-switch/

Reset switch:

http://lifehacker.com/5994036/add-a-res ... spberry-pi

Battery pack:

https://www.raspberrypi.org/forums/view ... 40&t=57868

colonel_panic
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Re: Unplugging the power from a Raspberry Pi?

Postby colonel_panic » Tue Dec 26, 2017 11:28 am

Years and years ago, I tried to start a company selling computers develop a computer for use on board boats without access to the mains. They were very energy efficient for the time, passively cooled and based on the AMD Geode (basically a Pentium 2 class computer, running at 500Mhz).

One of the things I did to try and reduce power consumption was replace the PATA hard disk with a Compact Flash card, which you ran through an adapter. One of the selling points of these was the fact that they wouldn't be damaged in the same way as conventional PATA hard disks if the power supply was interrupted in the way you are thinking. In fact, the manufacturers specifically sold the adaptors for testing new systems; they booted an OS with them, left it running for a while, and didn't bother shutting it down. CF cards were a disposable price compared to hard disks at the time.

My understanding is there is potential for damage to a mechanical hard disk if you cut the power suddenly, but this is not so much a problem with flash memory. However, if you shut your computer down with applications running that have unsaved changes, you are likely to lose those changes, so it's better to shut the operating system down.

I think causing meaningful damage is unlikely, though ash's solutions are much more elegant.

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kbongosmusic
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Re: Unplugging the power from a Raspberry Pi?

Postby kbongosmusic » Thu Dec 28, 2017 7:16 am

I've developed a few systems that could withstand power outage any time with linux. Flash obviously better than spinning hard-drive. Although the flash providers will warn you that you can get in a corrupt state with random shutdown, it rarely happens. Whereas spinning hard-drives I've had serious problems with in that regard. I arranged main working file system as read-only, and then separate rw disk/partition for select applications. I did x86, debian with custom setup, then voyage linux - which is essentially debian tweaked for embedded x86. This was a while ago, ext2 worked good. I would think rasberry pi would offer something similar, as this looks like the nice new embedded linux platform. Gotta love linux because you can build an appliance like this. All of the wi-fi routers are a working example. Screw windows/mac/android with their I own you mentality. Freedom rocks. Wish I had more time to play with stuff like this. Rock on. Let freedom reign.

stringrazor
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Re: Unplugging the power from a Raspberry Pi?

Postby stringrazor » Thu Mar 15, 2018 8:23 pm

My R-Pi has been part of my stage gear for a year. Using mididings, you can easily build a script that take can use any MIDI message to trigger a shutdown. I've just been activating "wifi tethering" on my phone for a connection and using VNC to shutdown after rehearsals and gigs. I recently started playing with the GPIO and maybe a switch would be easier, but it has to be idiot-proof. I sooner risk crashing it after use than accidentally turning it off during a gig.

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flappix
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Re: Unplugging the power from a Raspberry Pi?

Postby flappix » Fri Mar 16, 2018 5:16 pm

I set up my Pi with a read-only rootfs. Normally, I shut it down the regular way but sometimes the power cable slide off or I'm too lazy and just quit the power connection. Until now I have no issues with it.


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