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I have a disk over 2.1 GB in a system that has BIOS translation, that FDISK or other utilities see as either only 2.1 GB or as a much smaller disk, say only around 400 MB in size

Explanation: There is a hard disk over 2.1 GB in size being used in a system that supports BIOS translation. The disk's size is being presented as either truncated to only 2.1 GB, or it is showing up as a much smaller number like 400 MB for a 2.5 GB drive.

Diagnosis: The most likely cause of this problem is that while your BIOS supports translation, it is not correctly handling disks that have over 4,096 cylinders. There were some BIOSes that did not handle these larger disks correctly; this is one of the hard disk size barriers. Different BIOSes handle these larger disks differently when they aren't supported properly. Some simply truncate the disk to 4,096 cylinders so that the disk appears to be 2.1 GB in size, and others "wrap around" so that they show up as 400 MB (2.5 GB minus 2.1 GB). This is discussed here.

Tip: If this disk is showing up as 504 MB or 528 MB, this is a sign that BIOS translation is not functioning on the machine. Continue here.

Recommendation:

• Make sure that you are really seeing how much of the disk is being detected, and not just one of the partitions. In particular, there is a 2 GB partition size limitation under the FAT file system, which means you cannot make any disk volume greater than 2 GB even if the BIOS does detect all 2.5 GB of a 2.5 GB drive. See here for more on this limitation.
• You will need to "fix" your system's ability to handle these larger disks. In some cases, a BIOS upgrade may do the trick; contact your motherboard manufacturer.
• See this discussion of overcoming hard disk size barriers. If your hard disk is being "wrapped around" then you may be able to make use of a special jumper on the hard disk that will make it appear to your system as only a 2.1 GB disk. This wastes some of the space on the disk, so it is far from ideal.
• Contact your motherboard manufacturer for more ideas.

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