🚀 go-pugleaf

First, as you will see in my signature, I work for a company which competes
with the product in this article - HOWEVER, I want to put some more detail
into this discussion.  I do not wish to slight Golden Triangle in any way,
but simply to help users understand a new technology.

In article <1992Nov3.094642@p4.cs.man.ac.uk> brownc@p4.cs.man.ac.uk (Christopher C. Brown) writes:
>It's called Times Two from Golden Triangle.  It works by replacing your 
>current disk drivers with the TimesTwo drivers. After you install it, your 
>disk space is (looks) *actually* doubled!  I.e. the 80 meg LC they were 
>showing said 160M disk in the finder (well actually it said 10M used, 150M 
>free). 
>
	This is true - in more ways than one.

	First, TT is a REPLACEMENT driver, not an enhancement.  That means
that any current formatting software that you are using (SilverLining, Hard
Disk Toolkit, Drive7, etc.) is history - this completely replaces it on
your disk.

	What this means is not only is a previous investment no longer useful,
but you can not use the "special features" of these other drivers - such
as paritioning or security/encryption.  You only get a larger SINGLE partition,
unprotected drive.  

	Second, TT uses a non-deterministic methodology for reporting the
amount of free space on the disk.  It ALWAYS reports 2x (hence the product 
name ;) the amount of free space on the disk - no matter how much data is
actually compressable, it ALWAYS uses a 2x measurement.  

>I'm not a big technoweeny, but I'll try.  Disk drivers interpret system calls 
>to read and write information to the disk.  I.e. write (hello).  The driver 
>works out where to put it, translates it into binary, and writes onto the disk 
>(and vice versa for reads).  The new driver simply translates it into 
>*smaller* compressed binary, and vice versa.
>
	Actually, TT does more than just "compress" the data - it uses a 
number of techniques to increase the amount of "free space" on the disk
including using dynamic "block sizes" for you disk.  This will slow down as
disk as small blocks (which mean more free) means more to read, and so things
slow down.

>Since it works at such a low level, it is (i think) inherently compatible 
>with anything. It only really interfaces with the toolbox routines in ROM, 
>so all applications (they all work with the toolbox) work correctly and see 
>no change.  
>
	This is true for applications - there should not be any (or very
little) specific application compatibility.  HOWEVER, compatibility with
hard disk utilities will be a problem.  Things such as DiskLock & AME which
protect/encrypt the disk will not work in conjunction with TT.  Also, a 
disk optimizer may cause unpredictable results since the driver has special
block size rquirements.

	Also, if your hard disk goes bad (for whatever reason), you have to 
run a special "recovery program" BEFORE running whatever utility (Norton, CPS, 
PU) you would normally - that means carrying an extra disk in your emergancy kit.

>Summary:  I think it's brilliant.  I was laughing at the demo it seemed so 
>simple and obvious.
>
	There are some definate advantages to a driver level compressor
(though I don't belive TT has done it correctly, while others have), and
there are also disadvantages as I've tried to point out above.  Also, another 
important issue is "backing out".  Should you choose to back out of a driver
level compressor, you MUST back up the drive, and completely reformat - it
is not like removing an INIT based compressor like SpaceSaver or AutoDoubler.


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Leonard Rosenthol			Internet: 	leonardr@netcom.com
Director of Advanced Technology		AppleLink:	MACgician
Aladdin Systems, Inc.			GEnie:		MACgician