background fsck considered harmful? (Re: panic: handle_written_inodeblock: bad size)

Mikhail T. mi+thun at aldan.algebra.com
Thu Jul 22 17:14:29 UTC 2010


22.07.2010 12:50, Kirk McKusick ???????(??):
> If we did not have a better solution in the pipeline (journaled
> soft updates), I would agree with you that always doing a full
> check on small filesystems would be a useful enhancement. However,
> since we do have a solution that will work well for all sizes of
> filesystems in -current and expected out of the box with 9.0, I do
> not think that it would be useful to add this extra complexity
> at this time.
>    
The production-ready 9.x is at least a year away... Even when it ships, 
the journaled soft updates will not get into wide use immediately -- 
even if newfs enables that by default, people upgrading existing 
installations will, likely, leave the filesystem unchanged for a while. 
And the 7.x and 8.x installs currently in use will be around for many 
more years to come -- they should get this enhancement, in my opinion.
>> >  And a stern warning issued, when a background fsck is attempted -- for
>> >  whatever reason. Something like:
>> >  
>> >       background fsck, although faster, may be unable to detect certain
>> >       rare forms of filesystem corruption. You are advised to perform a
>> >       full fsck on %s on a regular basis. See fsck(8).
>> >  
>> >  should go into the right place under fsck_ffs/ -- not sure, where exactly...
>>      
> Since most folks do not look at the output from background fsck and with
> the changes noted above, I do not feel that adding this message would
> be all that helpful at this time.
>    
When there is a problem with frequent FS-related panics, more attention 
is paid to the start-up messages, I think... People are more likely to 
see that error message, for example, than they are to study the man-page 
(unless something directs them there).

Being "only" a ports-committer, I can not update fsck.8 -- someone else 
would have to do that.

Also, what about updating fsck_ffs.8 -- to specify, which of the 
inconsistencies are and aren't checked by background fsck?

Yours,

    -mi



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