cvs commit: src/sys/kern kern_shutdown.c

[Roman Kurakin]

Alfred Perlstein:

>* Scott Long <scottl at freebsd.org> [040721 09:57] wrote:
>  
>
>>It should be noted that syncing on panic is almost never a good idea.
>>The whole idea of panic() is to signal that the system has gotten into
>>an inconsistent and unrecoverable state.  Do you really want to trust it
>>to spam your drive with buffers that are in an unknown state via a set
>>of codepaths that are in an unknown state?  It's much better to just
>>step back and let fsck try to repair the damage.  I can't remember a
>>single time in the last 4 years when a panic actually successfuly synced
>>out all of the buffers and shutdown the filesystem, so it's not likely
>>that you'll avoid a fsck on reboot with this.
>>    
>>
>
>It's not about avoiding a fsck, it's about recovering the last 30+ seconds
>of disk activity.  Ie, files you've just created and such.
>
Just fresh view or one more crazy stupid idea ;-)

Why not to save those 30+ sec data and let user apply it manualy 
(probably this is
possible only for text data) at fsck time or later. We could create a 
disk in memory
put files that would be touched in to it and apply one by one file and 
see what
would happen. This may be usefull for critical data. And this sync_delta 
could be
saved in safe place like crash dump saved.

rik