Hard Drive "Full" but 150GB still available


Apr 8, 2009
I tried to run a defrag, but apparently I need 15% hard drive to do this. This was a little worrisome since I know I have a 300GB drive (WD Raptor) and would not have reached anywhere close to that. So I looked into System Information (stats below) and it seems I have used 130 of the 280 available.
I don"t recall having such a big partition for the OS, so 'm confused as to where I'm losing space.
Any advise/direction would be greatly appreciated.

Description Disk drive
Manufacturer (Standard disk drives)
Model WDC WD3000HLFS-01G6U0
Bytes/Sector 512
Media Loaded Yes
Media Type Fixed hard disk media
Partitions 1
SCSI Bus 0
SCSI Logical Unit 0
SCSI Port 4
SCSI Target ID 0
Sectors/Track 63
Size 279.46 GB (300,066,439,680 bytes)
Total Cylinders 36,481
Total Sectors 586,067,265
Total Tracks 9,302,655
Tracks/Cylinder 255
Partition Disk #0, Partition #0
Partition Size 127.99 GB (137,427,945,984 bytes)
Partition Starting Offset 32,256 bytes


Sep 22, 2008
empty recyle bin, delete restore points,.....
or just run ccleaner

"Partition Size 127.99 GB"
do you have more than one partition or unpartitioned space by chance


Jul 14, 2006
Is the drive using the NTFS format? If you used FAT32 then the partition size would be limited to about 132Gig or is there a jumper on your hard drive that limits the drive size to 132 Gig? Finally does your BIOS have a limit on the maximum size of hard drive? What size does the BIOS report the hard drive as?
The drive size you report suggests strongly that you have been limited by lack of what is called "48-bit LBA support".

The first version of LBA for access to hard drives, introduced in the 1990's, used a single 28-bit binary number to specify a location on the HDD. This allows 2^28 possible locations, or 268,435,456 of them. Each sector can hold 512 bytes, so that's 137,438,953,472 bytes. Now M$ defines a GB as 1024 * 1024 * 1024 bytes, so that disk space is called 128.0 GB. Toward the end of the '90's this was recognized as a substantial limit on disk capacity and a revised version of LBA was introduced that uses 48 binary bits to specify the location.

To use 48-bit LBA you need it supported in three places. One is the hard drive itself, and any drive made over 128 GB obviously has that. The second is the hard drive controller on the mobo. ALL SATA controllers have this. Most IDE controller systems since about 2000 have it. There are some older mobos still in use that do not, and some of those can be updated to get this ability by BIOS updates. The third place is in the OS. Windows XP in its original version did NOT have it - it was added with SP1 and all Windows since then have 48-bit LBA support.

If your hard drive unit was originally Partitioned and Formatted using Win XP original version or an earlier Windows, that would explain why the Partition created is 128 GB. Even if you later updated your windows OS to a recent version, that would not change the size of the Partition in use. It only will allow you to create and use new Partitions larger than 128 GB. This means that there is still something like 150 GB of unused space on the HDD marked as "Unallocated".

You appear to have four choices. One would be to back up all your data to another HDD unit, then re-install Windows (a newer version) to the original HDD but this time make it use all of its space for one Partition. Then you restore all your data to it. An easier version of this if you have a spare HDD unit would be to get cloning software and install it on your existing HDD. Then you clone it to the spare drive. Then you boot from the spare drive and re-clone back to the original, but this time you first Delete its existing Partitions and then have the cloning software NOT merely reproduce the Partition size - you must tell it to make the Partition on the Destination Drive (your original HDD) the full size of the disk. Thus you would end up with everything back on your original HDD to be used as your C: boot drive, but with a much larger size.

The second option, available in some of the newest Windows OS's (but not in XP) is to Expand the existing Partition to a larger size by simply adding on the Unallocated Space available.

The third option is to do the second option, EXCEPT that you use some third-party software to do the job, rather than have Windows do it. There are very good tools for this work - Partition Magic being one of them.

The last choice is to live with what you have, PLUS: use Windows' built-in tool Disk Management to go into the HDD and Create a second Primary Partition out of the Unallocated Space and Format it. That will become, in Windows' view, a completely separate new "drive" with its own drive letter name, fully usable for data etc. It just will not make your current C: drive any bigger. BEFORE you do this, however, IF you are still using Win XP original version with no Service Packs installed, UPDATE it to the latest version of XP, SP3.

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