The 137 GB Hard Drive Limit

The 137 GB Hard Drive Limit

ATA Interface Limit (128,000,000,000 bytes (128 GiB) = 137 GB) Barrier

*** also see Microsoft's article:

"How to enable 48-bit Logical Block Addressing support for ATAPI disk drives in Windows XP" - the article explains how you must be using SP1 (or SP2) and that Atapi.sys has been replaced by the SP2 version 5.1.2600.2180 (this is not the WinXP SP2 upgrade - oddly - the SP2 Atapi.sys file comes with the WinXP SP1 upgrade).

IMPORTANT User Tip: if you had a drive greater than 137 GB and could not see it all, but were using it anyway - and then you upgrade and get the SP2 ATAPI version - you will need to remove all partitions from your new drive before seeing all of it. This is a tip from a user on the Dell forum, and I have not tested this !!

Most of you will not run into this problem. It is for power-users only, who need huge drives. Especially for someone working with Video !! If you do need a drive greater than 137 GB, I would highly recommend getting a Serial ATA controller card (PCI card) from Promise Technologies. Make sure you have an empty PCI slot first, of course.

To get around past hard disk barriers, most modern hard disks are now no longer addressed using discrete geometry (cylinder, head and sector numbers) but rather logical block addressing and a sector number. However, even if we go away from the problems associated with assigning some bits in an address to cylinder number and others for head number and sector number, we eventually reach the limit of the addressability of all the bits taken together. In the case of the ATA interface, 28 bits are used for the sector number interface between the operating system, BIOS and the hard disk. This means a hard disk can have a maximum of 2^28 or 268,435,456 sectors of 512 bytes. This puts the ATA interface maximum at 128 GiB or approximately 137.4 GB.

The 48-bit addressing Fix

The workaround to this is to increase the LBA addressing bits from 28 bits to 48 bits. Upgrade your BIOS to the latest revision level. Most motherboard manufacturers have released upgrades that supports 48-bit LBA.

For Windows XP users, you must have SP1 or SP2 loaded !!!

Also, Atapi.sys in your %systemroot%\System32\Drivers folder, and then click Properties. 5. Note the file version on the Version tab. If Atapi.sys is not version 5.1.2600.1135 (a common version, even with SP1 loaded, is 5.1.2600.1106) then run the Hotfix from http://support.microsoft.com/kb/331958 .

Currently, there are three options to remedy the 137 Gigabyte barrier. Failure to implement one of the following installation options will result in data loss when trying to access the hard disk beyond 137 Gigabytes.

Installation Option 1. Upgrade the operating system to either Windows 2000 with Service Pack 3 (or newer) or Windows XP with Service Pack 1 (or newer) and download the Maxtor Big Drive Enabler software patch. The Maxtor Big Drive Enabler, once executed, will update the Windows registry for large drive support.

Installation Option 2. Download and install the Intel Application accelerator. The Intel Application Accelerator provides 48-Bit LBA compliant ATA/ATAPI controller drivers (IntelATA.mpd) and replaces the Windows 98/Me, 2000 and XP ATA controller drivers (ESDI_506.PDR). Intel is the only chipset manufacturer that we are aware of that offers a compatible controller driver for Windows .

IMPORTANT !!! This is not for older systems with older chipsets, such as the 440BX, etc. The Intel Application Accelerator only supports the following chipsets: 810, 810E, 810E2, 810L, 815, 815EP, 815G, 815EG, 815P, 820, 820E, 840, 845, 845E, 845G, 845GE, 845GL, 845GV, 845PE, 850, 850E, 860. The Intel Application Accelerator can be obtained at http://www.intel.com/support/chipsets/iaa/. If you have an unsupported chipset or do not want to upgrade the operating system then try the next solution.

Installation Option 3: Attach the large hard drive to an add-in Ultra ATA PCI adapter card with a 48-Bit LBA compliant BIOS and controller driver. The adapter card bypasses the system BIOS and operating system’s controller driver and uses its own BIOS and controller driver.

Using an IDE ATA/ATAPI controller that has a 48-Bit LBA compatible controller driver will allow safe use of large drives beyond the previous limits of 137 GB capacity.