Re: hdd defrag

[Mike Fedyk <mfedyk@matchmail.com>]

On Fri, Apr 20, 2001 at 08:28:03PM -0700, idalton@ferret.phonewave.net wrote:
> On Fri, Apr 20, 2001 at 04:54:57PM -0300, Peter Cordes wrote:
> > On Fri, Apr 20, 2001 at 11:14:35AM -0700, Jeff Coppock wrote:
> > > I was wondering if it's necessary to defragment ext2fs or reiserfs?  I do this on a regular basis with my Windoze machines.
> > > 
> > > What utilities could be used for this, if it's recommended?
> > 
> >  ext2 is smart, and does a good job of not fragmenting files.  search the
> > web, lots of good info is out there.  Reiserfs is also smart like that.
> > (BTW, it's the allocation algorithms in particular that are smart.  They put
> > new files where they will have room to grow without fragmenting.)
> > 
> >  If you have an almost-full filesystem, there won't be room to avoid
> > fragmentation, so you should avoid that.  ext2 is most efficient when less
> > than 90% full, or so.  (I don't know what a good cutoff value should be, but
> > 90% is probably reasonable.)
> > 
> >  There is an ext2defrag or something around, so you can use that if you want
> > to.  Most people never defrag their FSes, and have no problems with them.
> 
> My own experiences with defragging ext2 have generally been: Don't. On
> the other hand, if you happen to shrink an ext2 partition with some
> utility like Partition Magic (and I haven't tried ext2 resize yet) it'll
> actually help to run a defrag on it afterward. On the other hand, you
> can't quit in the middle of defragging, and you can't defrag the current
> root partition.

And you can't defrag a partition when it is in use/mounted.  Linux people
have generally designed the system so it doesn't need defrag, and haven't
put in the support for degrag except in extreme cases.  That's why you have
to unmount before defrag...

I have a partition that is root, and has gotten to 99% and back down to
about 80% usage.  Why wouldn't I want to defrag that partition?

> 
> -- Ferret
> who learned the hard way, when the power failed during a defrag once.
>

Maybe it would be safer to just copy everything to another drive and use that?

hmm, I need to repartition anyway, my 17GB root partition is too big...

Mike