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I plan to use a read-only filesystem to lose power without corrupting data. I know some routers are designed this way.

Are there any problems besides the filesystem I should be aware of?

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    Hey goldilocks, I posted in the raspberry forum because I care mostly for raspi specific implications regarding hardware failures. I know how to make read only fs installs. – Bryan Shadow May 7 '15 at 18:49
  • Well, "Is there anything else that can be damaged by sudden power loss?" is a totally fair question -- but it would be better on its own to make it easier to find for posterity. WRT read-only systems working on the pi, sure. "Snappy Core Ubuntu" (Pi 2 only) is read-only out of the box. – goldilocks May 7 '15 at 19:00
  • Actually if that is the focus -- I hope you do not mind that I edited this to make that focus clearer -- then I'll reopen it. – goldilocks May 7 '15 at 19:05
  • Nope its quite better. Also changed the title. – Bryan Shadow May 7 '15 at 19:53
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    The issue is not whether the filesystem is RO during power loss. The problem with (some) SD cards seems to be the browning out (lowering of the supply voltage below specifications) during power loss. (Or at least that is what I read somewhere.) – Ghanima May 7 '15 at 20:03
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Yes;

The raspberry pi originally had a firmware bug that would trash the contents of sdcards regardless of if there were writes or not. With modern/recent firmware versions the raspberry pi is fairly tolerant of power loss even when writing.

High CPU usage and cheap adapters is the most likely cause of sdcard corruption on modern firmware.

On power up some usb devices pull more than normal current and can cause the raspberry pi to not boot or act strange. To avoid this, isolate power sources, use a bigger power source, or don't use extra devices.

If there is a slight over volt, the raspberry pi can take some time (hours? I have not tried) of no power before it's willing to boot again.

The A/B+ and the 2 have better hardware power management and suffer less from these issues.

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