Re: [HACKERS] sorting big tables :(

On Wed, 20 May 1998, Tom wrote:

>
> On Wed, 20 May 1998, The Hermit Hacker wrote:
>
> >     One of the things that the Unix FS does is auto-defragmenting, at
> > least the UFS one does.  Whenever the system is idle (from my
> > understanding), the kernel uses that time to clean up the file systems, to
> > reduce the file system fragmentation.
>
>   No, that doesn't happen.  The only way to eliminate fragmentation is a
> dump/newfs/restore cycle.  UFS does do fragmentation avoidance (which is
> reason UFS filesystems have a 10% reserve).

    Okay, then we have two different understandings of this.  My
understanding was that the 10% reserve gave the OS a 'temp area' in which
to move blocks to/from so that it could defrag on the fly...

    Am CC'ng this into freebsd-hackers@freebsd.org for a "third
opinion"...am willing to admit I'm wrong *grin*