SATA Hard Drive Shows “Unallocated” or “Unformatted” after new XP Install

Long story short, the solution to this seems to be upgrading to the latest service pack. Apparently Windows XP (no service packs) can’t recognize certain sizes of SATA drive. Here is an excerpt from a web article, with more information:

… Last week, my desktop died, reboot looping and the whole works. tried many things, eventually ending in a reformat and reinstall of XP on my primary hard drive. This fixed the problem as far as making the machine work. but when i hooked my 300 gig SATA secondary hard drive back in, it shows as drive E, and unformatted (every time i try to open it it asks if i want to format… NOOO!). and disk management shows it as 128 gb. (bios sees it as 300 gb still)
… SomeJoe7777 06-03-2008 at 05:30:46 AM Show message

Have you upgraded your Windows XP installation to at least SP1 yet? XP RTM (i.e. no service packs) cannot recognize IDE/SATA disks larger than 137GB/127GiB.

If this is the case, remove the 300GB drive and install at least SP1 to your primary installation (SP2 with all updates or SP3 preferred). After that, plug the 300GB drive back in and see if your partition is now recognized.

Paperdoc 06-03-2008 at 08:48:37 PM Show message

I’m sure SomeJoe7777 is right. You had to re-install XP, and it’s likely it was not the latest version on the install disk. That 128 GB number is a big clue – that is the max HDD size the OS can deal with until you upgrade to SP1 or later to add what’s called “48-bit LBA Support”.

CompTIA_Rep 06-04-2008 at 12:08:53 AM Show message

You can enable 48-bit LBA support in Service pack 1 or earlier by editing the registry.

(source: XP reinstall, secondary SATA drive showing as unformatted.

Date Published: 2009-10-12
Date Updated: 2022-09-04

Eric Hepperle

Eric loves to write code, play guitar, and help businesses solve challenges with code and design.
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