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Bios Upgrades

USB Hard Drives and 48-bit LBA

We have received questions from users installing USB 48-bit LBA hard drives asking whether requirements involving Windows Service Packs and 48-bit LBA BIOS compatibility apply to these drives. 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. If you are having a problem with your USB hard drive not being recognized properly or at all, one thing to check is to make sure your motherboard supports USB 2.0. Some older motherboards only supported USB 1.1 and your USB hard drive may require USB 2.0.

48-bit LBA BIOS compatibility:

We can only think of two situations where 48-bit LBA BIOS compatibility would be needed with USB hard drives with capacities greater than 137 GB. One is to boot from a USB hard drive and the other is to partition USB hard drive from DOS. If you do not intend to do either of these, then you do not need the BIOS to be 48-bit LBA compatible. You may also find your BIOS does not support booting from a USB hard drive. On older systems, booting from USB devices is not supported. If USB device is not listed as a selection as a boot device in BIOS setup, then booting from USB is not supported. Regarding partitioning USB hard drives from DOS, we did a spot check of partition tools such as Partition Magic 8.0 and found partitioning USB hard drives to be supported but only from Windows and not from DOS rescue diskette version.

One problem we noticed trying to partition a USB hard drive from Windows 2000 (and probably XP) using Partition Magic was that the application would not allow us to partition and format the USB hard drive when the hard drive was configured as "dynamic". We had to configure the hard drive as "basic". Instructions for doing this:

From the Windows Control Panel, select Administrative Tools -> Computer Management
Under Storage in left window pane, select Disk Management
In right window pane, select Disk X which is USB hard drive and right click with mouse on this selection.
Select the option for configuring as basic drive.

HDINFO
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