Path: utzoo!attcan!uunet!lll-winken!decwrl!shelby!portia!name
From: name@portia.Stanford.EDU (tony cooper)
Newsgroups: comp.sys.mac
Subject: Re: Disk Defragmenter? (or Sum II vs DiskExpress)
Message-ID: <7242@portia.Stanford.EDU>
Date: 3 Dec 89 16:33:18 GMT
References: <1989Dec1.210947.5987@jarvis.csri.toronto.edu> <24664@cup.portal.com>
Sender: tony cooper <name@Portia.stanford.edu>
Reply-To: name@portia.Stanford.EDU (tony cooper)
Organization: Stanford University
Lines: 26

SUM II TuneUp has limitations that DiskExpress does not have. I quote from
the manual p6-3: "Normally, SUM TuneUp cannot defragment every file on your
hard disk". Not only is this true, the optimize volume usually cannot
defragment the free space fully either. I was once in the situation where
I wanted 700K of contiguous free space where I had 5000K of total free
space. TuneUp could not defragment all files nor could it defragment
enough free space to give me 700K of contiguous free space.

The reason for this deficiency is that TuneUp cannot defragment files 
(consider the free space as a single file) that are larger than the largest
piece of contiguous free space. This is because (think about it - you have
to work it out for yourself) files larger than the largest free chunk
cannot be defragmented unless some other file has its fragmentation
INCREASED (albeit temporarily). This is risky. TuneUp does not do it,
DiskExpress does do it. Hence DE can defragment all files of any size
and free space of any size. TuneUp reaches stalemate normally before it
finishes defragmentation.

So DE does more than TuneUp at increased risk. But DE does have the quick
optimize option that lets it work in the same way as TuneUp and with the
same safety. So DE is more powerful and versatile (and expensive) than
TuneUp. It was worth it for me because it gave me the contiguous space
that I wanted, whereas TuneUp would not.

Tony Cooper
name@portia.stanford.edu