hard reset impacts on ufs file system

[Kurt Lidl]

On 5/18/14 1:12 AM, Julian Elischer wrote:
> On 5/16/14, 10:44 PM, Ali Okan YÜKSEL wrote:
>> incident:
>> ==
>> file corruption after hard reset on FreeBSD 8.3
>>
>>
>> details:
>> ==
>> Hard reset examined on freebsd 8.3. after reboot libncurses.so.8 was 0
>> byte. And I couldn't login to system. It gave me error message about
>> /bin/sh - libncurses.so.8 corruption. (libncurses depens /bin/sh I guess)
>> I found the problem by using fixed shell.
>>
>>
>> solution:
>> ==
>> I copied libncurses.so.8 from another system. When I did it problem
>> solved.
> Unfortunattely libraries do seem to be one of the more common
> victims of this sort of thing but I have never worked out how.
> However,as you said, recovery is relatively easy by booting single
> user and specifying /rescue/sh as your shell.

My original guess as to why this seemed to always happen to
libraries was that the system damaged their entries when
attempting to update the atime on the files.

Two suggestions:  turn off atimes, make sure any write-cache
on your harddisk(s) is/are turned off.

-Kurt