After a power cut my machine cannot boot

Paul Smith phhs80 at gmail.com
Wed Sep 9 22:45:53 UTC 2015


On Wed, Sep 9, 2015 at 11:09 PM, Sam Varshavchik <mrsam at courier-mta.com> wrote:
>> >>
>> >> on a F21 machine, there occured a power cut. And now I cannot boot the
>> >> machine, and when I use the rescue mode and try to run again
>> >>
>> >> yum update
>> >
>> > I know I'm coming in late, and judging from other replies this probably
>> > won't work, but have you tried yum-complete-transaction?  I'd suggest
>> > using
>> > --skip-broken, but that only checks for certain errors in the files
>> > rather
>> > than doing what the name implies.
>> >
>> > Going off-topic for a moment, and presuming that dnf acts the same way
>> > (I
>> > don't, as yet, have a box using it.) should there be a bugzilla either
>> > complaining that the switch doesn't actually do what it says (e.g.,
>> > skipping
>> > to the next package if this one is broken instead of only being able to
>> > pull
>> > it out of the transaction if the signature (I think it is.) doesn't
>> > match.)
>> > or requesting that it be renamed to something more appropriate, with the
>> > current switch being left as an alias for the correct one to keep
>> > scripts
>> > from breaking.  I'm neutral on the subject, although I'd prefer that
>> > something be done to keep people from wasting time trying in cases where
>> > it
>> > doesn't apply.
>>
>> Thanks, Joe. I have just tried
>>
>> yum-complete-transaction
>>
>> but with no success: the error message ("/lib64/libidn.so.11: file too
>> short").
>
>
> This is a critical system library. It has been hopelessly corrupted. You
> cannot run anything. libidn.so.11 is a critical system library, used
> probably by 99% of binaries on an average system. Any command someone will
> suggest for you try won't work, because the command itself needs
> libidn.so.11, and it's broken.
>
> If you have another working system, it should be possible to recover this
> library using a rescue disk; by first fscking the filesystem to get it into
> a consistent state, and then meticulously restoring the corrupted files from
> another good system.
>
> However, this procedure does require a fairly good amount of technical
> experience and knowledge. Furthermore, all you know is that libidn.so is
> corrupted. You have absolutely no guarantees, whatsoever, that this is the
> only corrupted system library. After fixing it, it's fairly likely that you
> will discover that another critical system library is similarly corrupted. I
> can pretty much guarantee you that this is the case.
>
> Eventually, you will get to the point where you apparently restored all the
> critical files, and you are seemly able to boot, but probably won't be able
> to boot all the way through to the desktop, due to some less-critical
> libraries being similarly corrupted, or other kinds of critical files
> missing, but that doesn't come up until a later point in the boot process,
> and the error message is lost somewhere that's not easy to find. All you
> know that that the boot hangs, with no immediate indication as to what's
> broken.
>
> I'm just giving you the most likely scenario I think you will end up with,
> if you try to continue along the path of trying to salvage this system.
> Based on what you already wrote in this thread, I think the best thing for
> you to do is to simply reformat and reinstall. Using a rescue disk, it
> should be possible for you to salvage any individual files you need off this
> system, before reinstalling it, if necessary.
>
> And once you have everything reinstalled, invest in a good UPS so you won't
> have to do this again.

I thank you, Sam, and the other respondents. And yes, I can run almost
no program because of that file...

I will try sysresccd, as Heinz advises. In case that does not work, I
will reinstall the system. Fortunately, I have a backup of my home
directory and all important files!

Is there something, apart buying a UPS, that one can do in order to
minimize the severity of the damage that a power outage can cause?

Paul


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