Computer Science – Data storage and compression | e-Consult
Data storage and compression (1 questions)
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The advertised capacity of a storage device is typically expressed in powers of 1024 (e.g., 1 TB = 1024 GB), while the actual usable capacity is expressed in powers of 1000 (e.g., 1 GB = 1000 MB). This difference arises because of the way storage devices calculate capacity.
- Decimal vs. Binary:** Manufacturers use binary (base-2) to calculate capacity, while operating systems often use decimal (base-10). 1024 is closer to 1000 than 1024 is to 1000.
- File System Overhead: A portion of the storage space is used by the file system (e.g., FAT32, NTFS, exFAT) to manage files and directories. This includes metadata (information about files like name, size, and location) and allocation tables. This overhead reduces the amount of space available for storing actual data.
- Formatting: The process of formatting a storage device also consumes a small amount of space.
The file system essentially reserves space for its own operations, reducing the amount of space available to the user. Therefore, the advertised capacity is always higher than the usable capacity.