Re: Current state of filesystem features / improvements

[Antti Kantee <pooka%homeworld.netbsd.org@localhost>]

On Sun, Nov 28, 2010 at 07:18:59PM -0500, Greg Troxel wrote:
> 
> "Aaron J. Grier" <agrier%poofygoof.com@localhost> writes:
> 
> > I was my understanding that background fsck uses snapshots, which are
> > orthogonal to softdeps.  perhaps I am incorrect?
> 
> I believe that snapshots are for backups, and background fsck requires a
> fs that can operate in any state that could have been created by power
> loss.

You are both correct.  The kernel requires a non-corrupt file system
for mounting a boot time (softdeps) and fsck requires a non-changing
image for the duration of its run (snapshots).  At the end of the
fsck run the results are "merged".

(or at least that's how I understand background fsck without ever
having even peeked at the code)