hbearden :
All systems have a limit as to how may GB the BIOS can address directly. 128 GB (meaning 137,438,953,472 bytes) is common for systems dating from a few years ago. If you install a larger hard drive and put Windows on that you will be fine until Windows writes something important beyond that 128 GB limit. After that your booting will be unpredictable, up to and including not being able to boot.
There are two workarounds. One (recommended) is to limit the operating system (C:\) partition to 128 GB, or whatever your BIOS's limit is, and make one or more partitions out of the rest of your hard drive. (EaseUs Partition Manager is a great free tool for this.) This works because once booted, the BIOS has passed control to Windows, and Windows XP is able to address a larger HD than you will ever need.
Another workaround is to use what's usually called a disk management utility (but not to be confused with the "Disk Management" utility in Windows). Samsung has OnTrack, WD has Data Lifeguard, every HD manufacturer has one. They insert an extra "layer" into the boot process that allows your BIOS to address the full HD. The problem is that they are notoriously buggy, and your system will boot fine until one day it doesn't. Plus, booting into your Windows OS from media like CD's, floppies, etc., if you do that, will be very complicated or impossible unless you have made the media yourself to include that disk management software. It is much safer to go with the multiple-partition solution above.
Please note I have omitted a lot of technical detail and language to keep this discussion simple; please do not troll me. Look up "Logical block addressing" in Wikipedia if you want to know more. But to get the job done you don't need to know more or more accurately than I have stated here.
I am new to this forum. Like others, I had installed a WD 250GB drive into my older Compaq N800 laptop running XP Pro SP3, partitioned it to the full 250GB, and was lulled into thinking it was working fine, until one day it didn't (disk read error). Using EASEUS Data Recovery (a purchased product), I was able to recover my files, but many of which had been overwritten and were badly corrupted.
The most recent BIOS for my laptop (2005) doesn't display any information about hard drive parameters. The (cheap) program HDInfo verified the BIOS has limitations reading large drives (is not 48 bit LBA compatible) but little more. Using EASEUS Data Recovery, I learned my BIOS reports the drive as 240 heads, 63 sectors, and 17753 cylinders (240 * 63 * 17753 * 512 = 137.4GB). OK, my laptop BIOS has problems above 137GB.
Armed with that information, I used EASEUS Disk Copy to clone the original 80GB disk to the WD 250GB drive in an external USB case. This worked flawlessly, and the new drive booted first time and had one 80GB Partition (Drive C). Next, I installed and used EASEUS Partition Manager running in Windows to resize that partition. This time, instead of allocating all 250 GB to drive C (my previous mistake), I set the partition size to just under 137.4 GBits (=2^28 * 512), or around 127GB, as reported using Windows Explorer properties. Using Partition Manager, I then created a second partition that used the remaining space (drive E). So far, so good. However, you will forgive me if my confidence was shaken by my previous experience. Therefore, I contacted Western Digital to see if they would verify this approach (partition 250G in two logical drives, with C being under the BIOS limit), but I was told I need a DDO. Strangely enough, I also was told they no longer support Data Lifeguard Tools, which is the WD tool they supply to install a DDO.
I got some help from Microsoft,
Article ID 305098, which was written to address the 48-bit LBA limitation in
Windows 2000 SP2. It states:
"The operating system must be installed on the first partition that is smaller or equal to 137 GB when the EnableBigLba registry value is enabled but when you do not have a 48-bit LBA compatible BIOS. If you enable the 48-bit LBA ATAPI support by editing the registry setting, but you lack both a 48-bit LBA compatible BIOS and a hard disk that has a capacity of more than 137 GB, the hard disk continues to function as a standard hard disk with an addressable limit of 137 GB.
The operating system must be installed on the first partition that is less than or equal to 137 GB and the rest of the hard disk divided into one or more remaining partitions when the EnableBigLba registry value is enabled on a computer without a 48-bit LBA compatible BIOS that has a hard disk with a capacity of more than 137 GB. "
Per this article, if your computer BIOS is not 48-bit compatible, you should make sure the EnableBigLba registry bit is set (=1), install the OS in a partition that is below the BIOS limit (137 GB), and then create other partitions to use up the rest of the drive (just as hbearden wrote), at least with Windows 2000 SP2. I was unable to find a similar article about Windows XP SP3. One, older article about Windows XP SP1, Microsoft
Article 303113 came close. It reads:
"The registry value EnableBigLba is enabled without a 48-bit LBA compatible BIOS, but you have a hard disk with a capacity that is larger than 137 GB. If you enable 48-bit ATAPI support in the registry and you have a hard disk that has a capacity that is see comment than 137 GB, but you do not have a 48-bit LBA compatible BIOS, only the first 137 GB of the hard disk are addressable.
The remainder of the hard disk is not used."
The article has typos, but it at least validates the approach of restricting the C drive size to 137 GB if your BIOS is not 48-bit LBA compatible. As for the rest of the space on the large drive, the article is vague: "the remainder of the hard disk is not used." Not used... does that mean not used by the BIOS, by the OS, by Windows? And that was SP1, whereas we are now at SP3. If Windows XP SP3 works like Windows 2000 SP2, then dividing the rest of the disk into one or more partitions should work safely (as hbearden says). Does anyone know of any technical article or statement from Microsoft, a computer manufacturer, a hard drive manufacturer, or any other source that states for Windows XP SP3, if your computer BIOS cannot be made 48-bit LBA compatible, you can restrict the first partition (drive C) to the BIOS limit (in my case, 137 GB) and then safely divide the rest of the drive into one or more partitions (logical drives)? Has anyone had any problems doing this?