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Document ID: VLAR-442NEV

Hard Drives - Definition of storage space

Applicable to: World-Wide

IBM, much like hard drive manufacturers everywhere, define a GB (Gigabyte) as 1 billion bytes, or 1,000,000,000 bytes.

Some software that reports formatted capacities report hard drive capacity a different way, based on how computer memory has been measured over the years. Computer memory is based on the concept that a Kilobyte is not a 1,000 bytes but rather 1,024 bytes. This is because of the different way in which memory has been addressed, in binary terms, since the beginning of computing.

In like manner, these programs (using memory terms) define a Megabyte at 1KB X 1KB, or as 1,048,576 bytes rather that 1,000,000 bytes and a GB as 1,073,741,824 bytes.

Consequently a drive sold by IBM or a hard drive manufacturer with a capacity of 9.1GB in our terms, or 9,100,000,000 bytes, will be measured by some programs to have approximately 7.37% less capacity when expressed in bytes, 4.86% less capacity when expressed in Kilobytes, or 2.4% less capacity if expressed in Megabytes. For example:

9,100,000,000 decimal bytes divided by 1.048576 equals 8,678.436+ binary Kilobytes, which some customers might think is equivalent to 8.67 MB.

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under 1 GB, 1.x GB, 2.x GB, 3.x GB, 4.x GB, 5.x GB, 6.x GB, 8.x GB, 9.x GB, 10.x GB, 16.x GB, 18.x GB




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