Dick said:
Please explain "While you might have generated a 1 GB file
consisting of the letter "a", there isn't much to compress. Look at
it this way..." Maybe your explanation will illuminate why
WindowsXP/SP2's drive compression does not result in more space.
Both WinRAR and zip knock the 1 gb file to about 40 megs, a 250-to-1
ratio. There is a LOT of compression going on with a 1 GB file the
letter "A."
To understand how compression routines work, visit
"computer.howstuffworks.com" and you will see my reasoning.
I like to understand a good bit, testing is not "playing games." It
leads to understanding.
First - if you only took the 1GB file with just one instance of the letter
"a" in it down to 40MB with RAR - you did something wrong.
Use 7-Zip and you'll gain even more compression.
However - what your original question was about was using the built in
compression of Windows XP - or NTFS compression. With NTFS compression, the
purpose is *not* to compress it as small as possible - because that would
just increase the amopunt of time it takes to actively access the file with
the operating system later.. The goal is to compress "a little" to gain "a
little" space. While compressing some files with RAR or 7-Zip will give you
phenomenal differences in size.. (I recently compresses a 7.5GB Outlook PST
file to 4.48GB with RAR and all the way to 3.4GB with 7-ZIP) - the time it
takes to decompress and use that file again is not a worry.. However - when
you are talking system files, used applications and active documents, etc -
you really don't want to decrease the performance of the machine as it tries
to crank on your super-compressed files.
For reference - on a 3.73GHz dual-core system with 2GB memory and a RAID of
two 160GB SATA drives - the 7.5GB files took 1.5 hours to compress with
either application (RAR or 7-Zip) and took 12-20 minutes to decompress (I
was still using the computer when doing the decompression test - so I gave a
range there.) Yes - the file is much larger than any you will have in a
compressed NTFS system - but you have to remember - it not only has to
decompress one file - but all those others it is linking to it to use (DLLs,
etc.) And this would be continuiously going on if you did the entire
drive.. So it adds up to seconds pretty quickly.. If you want to know how
annoying seconds can be - remote into someone's machine with dial-up and
click on the start button like you are used to doing locally.. After a few
times - annoying.
Put quite simply - expecting NTFS compression to equal compression done for
pure storage/transport is ludicrous. They have two different purposes - one
purpose (the NTFS compression) has been replaced quite nicely by inexpensive
(relatively) larger hard disk drives.. And not many people can fill up the
amount of space they could add to their personal computer and actually say
they are actively using all of it - so they cannot possibly back it up and
erase it off the system at this time. Movie animators - maybe - but they
are not using home systems! heh
When a compressed file is opened, only the part being read is decompressed
to memory where it is worked with in an uncompressed state. Then when you
close the file, it is automatically compressed again. You may notice that
compressed folders and files take a bit longer to open and close than
uncompressed ones. For this reason, it is best to use compression on folders
and files you rarely access but which you prefer to store on your hard
drive. In other words - I would think that if you are that deathly close to
needing space - it's time to save up the $60 to $150 and get a 100 to 300GB
extra drive. 750GB drives are still heftily priced (not overly so) at $400.
Testing has been done on this for decades. I remember "drvspace" before it
was integrated into Windows 95. I used it. It had a purpose - because
prices and drive sizes were juxtaposed.. 200MB-850MB drives were expensive
buggers. It caused performance problems - but you lived with them because
you couldn't save up the $100's for a new drive. Now - if that is your
excuse - fine - for a few months.. But surely if you could have afforded the
system in the first place - you can afford another $100 to double your space
and not lower the performance that your hard-earned money got you to.
Compression should be used for rarely used files - and then - you can use
the best compression around and decrease it easily by more than 50% in size.
Compression used for more-than-rarely-used files just doesn't make sense
with today's hard drive sizes. the gain in space, so you can say, "I have
the same stuff as you and an extra 5% free space too.. hah!" just doesn't
even out with the, "hah.. yeah - but it takes me 8 seconds to boot and 1
second to load Word.. Look - I've typed my document and saved, come to the
party when Word finishes loading." *grin*
Then I