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FAQ's

The following are Frequently Asked Questions about 48-bit LBA:

3. I have a 250 GB drive connected to a Highpoint HPT372 controller on my motherboard. I'm using Window XP with SP1 and according to my motherboard vendor the BIOS and drivers I'm using support 48-bit LBA but I'm still having problems with data becoming corrupted on the hard drive. What's wrong?

4. The documentation for the partition utility provided with my hard drive states that the hard drive can be used without a 48-bit LBA BIOS because the software installs a Dynamic Drive Overlay (DDO). Why do I need to upgrade my BIOS to support 48-bit LBA?

5. I've installed my 48-bit LBA hard drive, made sure the BIOS supports 48-bit LBA, and upgraded Windows to the latest Service Pack, yet Windows and all the partition utilities I've tried still only recognize a maximum of 137 GB of the hard drive? What's wrong?

6. My 48-bit LBA hard drive is installed using a PCI ATA controller card and I've upgraded Windows to the latest Service Pack, yet Windows and all the partition utilities I've tried still only recognize a maximum of 137 GB of the hard drive? What's wrong?

7. If Microsoft is not providing any Service Packs to Windows 98, 98SE, or ME to support 48-bit LBA hard drives, are there any other options to make my 48-bit LBA hard drive work with these versions of Windows besides what you've listed on this site?

8. I have a 48-bit LBA hard drive installed on my system and I would like to move it and install it on another system so I can access the data on the hard drive using the new system. Is there anything I should be concerned about or pay attention to?

9. If Intel Application Accelerator is only for use on motherboards with Intel chipsets, do other chipset vendors have drivers for their chipsets?

10. I have a USB hard drive greater than 137 GB. Do the same requirements as IDE 48-bit LBA hard drives apply? What Windows Service Packs do I need installed and does the BIOS need to support 48-bit LBA? What about Firewire hard drives?

11. I need to do a new install of Windows 2000 or XP to 48-bit LBA hard drive but I have an older Windows 2000 or XP install CD without latest Service Pack to support 48-bit LBA hard drives. Do I need to purchase a new install CD of Windows 2000 or XP?

12. My 200 GB hard drive is only regocnized as 186 GB. Why is the capacity of my hard drive being reported less than the full size of the drive reported on the box?

13. Can I use a drive image program to migrate Windows 2000 from an existing hard drive to a larger 48-bit LBA hard drive?

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FAQ Details:

1. If the issue with 28-bit versus 48-bit LBA means hard drives can only be used up to a maximum capacity of 137 GB, why can't I just partition my 48-bit LBA hard drive into multiple partitions each less than 137 GB to get around the problem?

That will not work. If you try it and your system does not meet the requirements necessary for 48-bit LBA, data can become corrupted on partitions which extend beyond the 137 GB limit. The issue with 28-bit versus 48-bit LBA involves the absolute sector addressing on the hard drive not simply the address relative to the beginning of each partition on the hard drive. For example, let's say you have a 160 GB hard drive where you have created two partitions. The first is 137 GB and the second 23 GB. In order to properly read and write data to the second 23 GB partition, 48-bits of address are needed to access the correct sectors on the hard drive. Without 48-bit LBA support, drivers with only 32-bits of addressing will only be capable of addressing up to 137 GB on the hard drive.

2. I've installed a 48-bit LBA hard drive on my system and upgraded everything as necessary to properly support 48-bit LBA. Something has now happened with my system where I now need to re-install Windows to fix the problem. Do I risk losing the data on my hard drive?

There very definitely could be a problem with you corrupting or losing the data on your hard drive. It depends on a number of factors including how you have the hard drive partitioned, the version of Windows you are running, and what you have for install media to re-install the version of Windows you were runnning. Here's a couple of examples:

Case 1:

You are running Windows 2000 Service Pack 3 installed to a 160 GB hard drive with a single 160 GB partition. When you originally installed Win2K, you used an installation CD which does not include SP3, installed it to a single 130 GB partition, upgraded to SP3, then used a third party partition tool to resize and increase the partition to 160 GB. You now need to re-install Win2K and all you have is the original Win2K installation CD which does not include SP3.

In this case you definitely risk corrupting and losing data. The problem here is that if you attempt to re-install Windows 2000 from an installation CD which does not fully support 48-bit LBA, the installation could very likely corrupt the data on the hard drive because it does not contain the proper drivers and tools to correctly access a 48-bit LBA hard drive.

Case 2:

You are running Windows XP Service Pack 1 installed to a 160 GB hard drive with a single 160 GB partition. WinXP was originally installed from an installation CD which includes SP1. You now need to re-install WinXP with this same installation CD.

In this case, in theory, you should be safe and not risk losing your data by re-installing Windows.

So what should you do if you need to re-install Windows if your data involves a 48-bit LBA hard drive? If you absolutely cannot risk losing or corrupting your data, our recommendation is to play it safe. You should re-install Windows to another hard drive first. Make sure it is upgraded to fully support 48-bit LBA, then attach your original 48-bit LBA hard drive to the system as a second hard drive where you can now safely access the data on the drive. Another option is to create a new Windows install CD with latest Service Pack using a technique know as slipstreaming. For more information, consult FAQ here. There may be other options available to you if you are careful and know what you are doing. Hopefully resources available on this site will give you some ideas.

Highpoint provides support for the HPT372 controller through an option ROM which is embedded in the AwardBIOS system BIOS. The motherboard vendor claims the system AwardBIOS fully supports 48-bit LBA, but in this case since the hard drive is connected to HPT372 controller on the motherboard, you also need to make sure that the Highpoint option ROM BIOS also fully supports 48-bit LBA and what version of this option ROM is embedded in the system BIOS ROM. Highpoint claims 48-bit LBA is supported with version 2.1 of their option ROM and the user who submitted this to us was using version 2.32. However, after checking further with Highpoint they recommended a newer version 2.34 of their option ROM which unfortunately is not available with any BIOS update available from the motherboard vendor. You can try contacting the motherboard vendor about the problem to see if they can provide an updated BIOS with a newer version of the Highpoint option ROM. If they cannot help you, try contacting eSupport.com about the problem. Explain to them that you need a BIOS upgrade with an updated HighPoint option ROM. Their engineering staff may be able to help you out.

A Dynamic Drive Overlay (DDO) is software which many partition utilities will install on the hard drive to enable support for 48-bit LBA when the BIOS does not support 48-bit LBA. Using a DDO can be an alternate method for using a 48-bit LBA hard drive with Windows. However, there are disadvantages to using a DDO and they can cause problems especially later on if you move the hard drive to another system. The following contains further information:

http://www.pcguide.com/ref/hdd/bios/over_DDO.htm

We do not recommend using a DDO and you will not find any further information about using a DDO with 48-bit LBA devices on this site. If you are interested in exploring this option, consult documentation provided with your hard drive and the manufacturer's web site.

Check the documentation for your hard drive to see whether the drive has a jumper which limits the capacity to 137 GB. Some hard drives have this jumper which they recommend be set if the system does not properly support 48-bit LBA. For example, the Western Digital 160 GB hard drive has one of these jumpers which is labeled "4092 Cylinder Limit".

Also, check for driver update for IDE controller you have hard drive connected to, especially if IDE controller is not part of basic chipset such as a HighPoint RAID controller. The majority of cases where 48-bit LBA hard drive is not recognized at full capacity is due to the Windows driver not supporting 48-bit LBA. For driver updates, we recommend the Driver Agent service at www.driveragent.com .

Check the manufacturer's web site for an updated Windows driver.

Rudolph Loew has created a patch for Windows 98/98SE/ME. The High Capacity Disk Patch Program patches Windows 98/98SE/ME to provide direct support for hard drives larger than 137GB without requiring a controller card or the Intel Application Accelerator which can only be used with an Intel chipset motherboard. The patch installs support for the 48-Bit addressing mode required for hard drives larger than 137GB. We have not tested this patch ourselves and thus cannot provide any recommendations positive or negative as to it's use. You will find this patch at http://rloew1.no-ip.com/

Besides the Intel Application Accelerator which requires a motherboard with an Intel chipset, drivers for other chipsets may be available. We have been informed by one user that VIA has drivers which support 48-bit LBA for their chipsets. For latest driver list check out Drivers section under 48-bit LBA Tools & Drivers section on the left.

Careful here! Whenever moving a 48-bit LBA hard drive to a new system it is absolutely critical to make sure the new system is fully 48-bit LBA compliant. If it is not, it is highly likely the data on the hard drive will become corrupted and forever gone. We have received reports from some users where exactly that has happened. Unfortunately, helping recover the data is beyond the help we can provide here. If you value the data on your hard drive, our suggestion is to follow steps to safeguard your data first before moving the hard drive. That means backup your critical data to alternate storage using a backup application or copy your critical data to another hard drive. Then make sure the new system is fully 48-bit LBA compliant before you move the 48-bit LBA hard drive. Also, it's best to try and use the same version of Windows between the old and new systems or at least do not use an earlier version of Windows on the new system. For example, you could get into trouble if you are using your 48-bit LBA hard drive with Windows XP and you would like to move it to another system which is running Windows 98 SE.

9. If Intel Application Accelerator is only for use on motherboards with Intel chipsets, do other chipset vendors have drivers for their chipsets?

We have been informed by one user that VIA has drivers which support 48-bit LBA for their chipsets. For latest driver list check out Drivers section under 48-bit LBA Tools & Drivers section on the left.

We could not find anything in the Microsoft Knowledge Base regarding USB 48-bit LBA hard drives and Windows. The following information is from our own testing.

With Windows 2000 and XP, you do not need any Service Packs installed or the EnableBigLba registry value. Windows should recognize the full capacity of the hard drive and you should be able to partition and format to full capacity. If you are not able to see full capacity of the USB hard drive, then look for a driver update from the manufacturer of the USB enclosure. If that is unknown, you may be able to find a driver update from the Driver Agent service at www.driveragent.com. With Windows 98, you will need to install drivers provided by the USB hard drive manufacturer if Windows 98 is supported. For more information about USB 48-bit LBA hard drives click here.

Regarding Firewire hard drives, we do not have a Firewire hard drive to test and verify results. However, we expect Firewire hard drive requirements will probably be the same as those for USB hard drives. If anyone finds this not to be the case and has some interesting results, please pass it along to us so we can share it with others.

If you have a standard Windows install CD and access to a CD burner, then you can make a newer Windows install CD with latest Service Pack using a technique known as slipstreaming. It is the process of making a new Windows 2000 or XP disk with any Service Pack or hotfix on it that you choose. It is perfectly legal, and is even endorsed by Microsoft for corporations. There are many good guides on the net about the exact procedure. Examples can be found at:

http://www.winsupersite.com/showcase/windowsxp_sp2_slipstream.asp
http://www.windowsnetworking.com/articles_tutorials/Slipstreaming-Windows-Service-Packs.html

When the process is finished, you are left with a new copy of the Windows 2000 or XP installation cd with the Service Pack integrated. This means that you will not notice the problems of the 130GB limit in the first place and will be able to do repair installs. The only exceptions are that not all restore cd's that come with laptops can be used to slipstream and it must be a proper Windows 2000 or XP disk to start with.

12. My 200 GB hard drive is only regocnized as 186 GB. Why is the capacity of my hard drive being reported less than the full size of the drive reported on the box?

The difference is due to two different number systems used to express units of storage capacity, binary and decimal. The hard drive capacity reported on the box by the hard drive manufacturer is based in decimal. Windows reports capacity based in binary. The following is an excerpt from a Seagate Knowledge Base article:

There are two different number systems which are used to express units of storage capacity; binary, which says that a kilobyte is equal to 1024 bytes, and decimal, which says that a kilobyte is equal to 1000 bytes. The storage industry standard is to display capacity in decimal. Even though in binary you have more bytes, the decimal representation of a Gbyte shows greater capacity.

The following table is an excerpt from a Western Digital Knowledge Base article which shows differences in capacity reported for various hard drive sizes:

Drive Size in GB	Approximate Total Bytes	Decimal Capacity (bytes/1,000,000,000)	Approximate Binary Capacity (bytes/1,073,724,841)
10 GB	10,000,000,000	10 GB	9.31 GB
20 GB	20,000,000,000	20 GB	18.63 GB
30 GB	30,000,000,000	30 GB	27.94 GB
40 GB	40,000,000,000	40 GB	37.25 GB
60 GB	60,000,000,000	60 GB	55.88 GB
80 GB	80,000,000,000	80 GB	74.51 GB
100 GB	100,000,000,000	100 GB	93.13 GB
120 GB	120,000,000,000	120 GB	111.76 GB
160 GB	160,000,000,000	160 GB	149.01 GB
180 GB	180,000,000,000	180 GB	167.64 GB
200 GB	200,000,000,000	200 GB	186.26 GB
250 GB	250,000,000,000	250 GB	232.83 GB
300 GB	300,000,000,000	300 GB	279.40 GB
320 GB	320,000,000,000	320 GB	298.02 GB

For more information consult:

Seagate Knowledge Base article here.

Western Digital Knowledge Base article here.

13. Can I use a drive image program to migrate Windows 2000 from an existing hard drive to a larger 48-bit LBA hard drive?

The following tip was submitted to us by another user:

One other way to get a Windows 2000 install to work with a larger drive is to kind of trick it. Install it on a smaller drive, patch it, enable the 48bit LBA support, and then use Norton Ghost to copy the drive image from the smaller drive to the 300GB (or whatever) drive. This is handy if you have a drive image program but not a drive partition program. Once it gets copied over to the new drive, it will see all 300 GB as the main drive.

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