Solved: XP Pro - Partition/Correct GB display

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Dear Prudence

Thread Starter
Sep 26, 2007
:eek: Hi

I've installed XP Pro on a new 320GB hard drive.

From the Boot CD setup I selected;

20GB for C: drive (for XP)

80GB for D: drive (for programs etc).

XP has now installed - and I want to now allocate a partition to the remaining space.

I've read that you can give each drive 4 partitions.

When I have the below sorted - I will be adding another 320GB drive as a slave.

(all ATA drives - not SATA)

I have 5 questions;

1) Can you have 4 partitions - i.e. C: D: E: F: ?

2) Do you think from the info below, that XP is displaying the FULL space
on the drive.

3) I'm confused why the whole of the Unallocated space is not shown
because 27.99 GB is shown as Free space (of which I did not set up)

4) I seem to be missing 21.91 GB (see below)

5) If I can have 4 partitions on Disk 0 - can I then have 2 partitions on
the slave drive - drive 1 (I'm guessing it would be number 1)

From Disk Management this is what is displayed;

Disk 0
(C) 20.00 GB NTFS Healthy (System) (Primary partition) 14.59GB Free Space
(D) 80.00 GB NTFS Healthy (Logical drive) 79.78GB Free Space

27.99 GB Free space (Free space)
170.10 GB Unallocated (Unallocated)


Adding up gives me a total: 298.09 GB - missing 21.91 GB ??

Thank you in advance.



Somehow I think I have messed up at the XP installation stage.

Sorry a few more questions;

Can I convert the 27.00GB Free Space to be part of the 80.00GB Logical Drive?
As I cannot see the point of having a new Logical Drive of just 27.99GB !!

When I right click the Unallocated Space of 170.10GB, it says: New Partition

Could someone clarify - if I say yes to New Partition - will that then allow
me to create another Logical Drive?

I'm trying to limit any damage to my drive if it crashes - which my last
drive did, and it's taken 6 weeks to get the system up and running again.
(New HD - New RAM - New motherboard - New CPU - New OS (XP Pro)).

Thanks again.
Sep 1, 2007
OK, let's open the "missing GB" can o' worms first...

There are dozens of explanations for why HDDs claim to be Size "X" (in GB), but they only hold (approx .) Size "X" MINUS 7%...

Let's do the math; you'd expect that an average 100GB HDD would hold 100GB of data, but when we do the math, we see that 100GB - 7% = 100GB - 7GB = 93GB of ACTUAL capacity.

Now, let's put a 320GB HDD into the equation; 320GB - 7% = 320GB - (approx.) 21.91GB = 298.09 GB of USABLE space on the 320 GB HDD... IOW, since the HDD makers fudge the numbers, the USER "loses" space in the transaction...

In a nutshell, you're not REALLY missing 22GB of capacity on that 320GB HDD; it was never there in the first place...

See this article for more information:

Now, on to your next questions...

You can have up to four PRIMARY partitions on a single HDD; since you've mentioned a "Logical Drive", I get the feeling you made a single Primary partition, followed by an Extended partition, and then possibly set up a Logical partition within the Extended partition...

Converting the 27GB partition to merge it with the 80GB partition will most likely require 3rd-party software (such as Partition Manager); though there ARE some other ways to convert / merge / create / delete HDD partitions using specialized versions of Linux, they can destroy data, and you run the risk of losing ALL of your data on the ENTIRE HDD if something goes wrong, as it often does... How do I know that? I use Linux to manage partitions almost every week, and I frequently run into problems, because I work on HDDs that were not properly partitioned by the client...

You can learn a LOT from these links, starting here:

Followed by this one:

as the least you need to know, though in truth, I'd recommend that you read the ENTIRE guide (which begins here):

whenever you have some free time... and no, I'm not joking. Reading that guide will answer just about any question you'll ever have...

More information which can help you accomplish your goals of partitioning your HDD:

Though you will encounter this advice all over the 'net, let me include it here: Make SURE you have a COMPLETE backup of ALL of your critical files BEFORE you begin trying to partition your HDD, or you can lose ALL of your data!

Well, best of luck; I hope I've answered some of your questions; I'm sure the HDD guide at StorageReview will cover the rest of them... Let us know how this turns out for you...
May 12, 2007
It might have something to do with if you don't have SP1 or SP2 installed windows xp only supports hard drives up to 137 GB. the hard drive can be any size after you install SP1 or 2. kinda explains why it says 27.99 gb free. if you add C: and D:, its 100, which leaves approx. 37 gb's left that winxp can use. i know its not exactly 37 gb it says is free but 27.99 gb is pretty close. hope this helps.

good luck

Dear Prudence

Thread Starter
Sep 26, 2007
Thank you for your help.

I now understand where the missing space went.

I have bitten the bullet and right clicked the 170.10Gb unallocated space via
Disk Management.

(I need the 170Gb urgently to move data from another 320Gb drive which I managed to copy to before original drive crashed).

It only allowed me to create a Primary Partition - of which I've done, and is now formatting.

After it has formatted I hope it might allow me to split this into two - if not I can live with that.

I will get Partition Magic to deal with the free space 27.99Gb.

Thanks - Stephen
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