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Kubuntu 15.10 - Single OS - Desktop Computer

After a power failure the computer will only boot to Emergency Mode Screen - I have tried all the options listed on that screen - It still goes back to Emr. Mode.

I have tried booting to a live usb and using terminal to fsck - as here "Welcome to emergency mode!" Think it is a fsck problem

No change.

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No.

You hardly ever need to re-install. Period.

When the operating system is broken 99% of the time it should be possible to fix any problem if the problem is software related. Either from the grub rescue prompt or from a live session. The problem though is what to fix and how long it takes to find the problem, diagnose is and fix it. My system I can re-install within 19 minutes so if I do not have the time to do track it down I might opt to re-install myself.

journalctl -xb is the key here. You need to check the log file, happen to spot the line that is the one making it stop and find a solution for it. You need to do this before re-installing. See if you can and check the web for possible fixes. Otherwise might it a topic on AU.

But ... the problem might be hardware related. And if it is you got bigger issues than re-installing the operating system. Power outages tend to break hardware.

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  • Thank you - i tried journalctl -xb again and after a few times and it worked finally - from that i found the red text and removed the entry - all working again. – Dylan Nov 25 '15 at 13:33
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Hardware write buffering can cause you to have corruption when power is cut.

Linux is quite aggressive by default and enables write buffering in your hard drive. It doesn't help that much, and definitely doesn't help enough to risk corruption. Different drive firmwares can be more aggressive or more conservative.

To disable it, change these lines of your /etc/hdparm.conf:

# -W Disable/enable the IDE drive's write-caching feature
write_cache = off

by editing it with something like sudo nano /etc/hdparm.conf.

With write_cache off, you should be a lot more resilient to power cuts.

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  • Thank you - I will research that a bit further. I don't think though that the problem is with write-caching, I also use windows 7 with write caching and it started up fine after the power failure. – Dylan Nov 25 '15 at 8:14
  • @Dylan This isn't global write cache disabling. It is disabling the "trust" that the drive will really write something to a magnetic disk. With write cache on, it is considered "done" when it is in the write buffer memory in the drive. With write cache off, it is considered done when it is written to a magnetic surface. Filesystem writes will "cache" just fine either way. – doug65536 Nov 25 '15 at 8:29

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