Hard Drive Capacity Vs. Available Disk

How big is that drive?

The capacity rating for hard drives sold by GOLDENRAM is in accordance with the rating supplied by the hard drive manufacturer. The actual available hard disk space will vary according to a number of factors.

OS Efficiency

The single most significant factor is the Operating System or OS. Different operating systems use different amounts of disk space for the basic operation and maintenance of the information stored on the drive. Microsoft's DOS is one of the least efficient operating system as far as hard drive usage is concerned. DOS can use more than 20% of a disk drives space for it's partition table, FAT, and boot record. Other operating systems use different techniques to maintain the hard drive and are more efficient in their hard drive space usage. However, in the worst cases, a 1 gigabyte drive has it's available space reduced to 800 megabytes by the simple application of a DOS partition and format. Even though the drive has no user files on it.

Parameter Efficiency

Another variable is the hardware configuration. A drives maximum capacity is determined by a set of parameters that describe how the drive and computer will interact. In some cases, a single increment change to a single parameter can change the total capacity of the drive by over 100 megabytes. Some hard drive controllers and some computers are not capable of utilizing the correct parameters for a particular drive. In these cases, an automatic or manual adjustment of the parameters must be made. These adjustments may not yield the full capacity of the drive.

10^6 vs. 1024^2

The final factor determining a drives capacity is how the drive is rated by the manufacturer. Some drive manufacturers have determined that 1 megabyte is the equivalent of 1 million bytes. Other manufacturers call 1 megabyte the equivalent of 1024 bytes times 1024. Computers store information in RAM and utilize hard drive space according to the second rating system because of the binary basis of computers. By using the '1 million bytes per megabyte' rule, a drive can be described as being larger. Here's a table showing some comparisons of different drive sizes using both rating systems.

*Assuming 1 gigabyte is equal to 1000 megabytes

The drive ratings are the most confusing since the rating system is subjective. DOS normally reports megabytes available using the 1024 * 1024 rating system. Both rating systems result in the same storage capacity. One Byte of data uses one Byte of hard drive space regardless of how many Bytes per megabyte the manufacturer says there are.

What does all this mean to the end user?

Well, on a small drive, say in the 210MB range and under worst case conditions. The actual available hard disk space may be as low as 180MB. An apparent loss of 30MB. On a 2 gigabyte drive and under similar worst case conditions the loss can be as much as 500 megabytes!!! That means less than 1.5 gigabytes of available space.
Each of these factors vary widely. With the most efficient operating system, optimal drive parameters and a megabyte Equivalency that matches that used by the operating system, an apparent loss of less than 5% is achievable.