The smallest unit of space on a hard drive is a "bit". Eight bits make a byte, which is the basic unit. Half a byte is (appropriately) called a "nibble". One thousand and twenty-four bytes make up a kilobyte, 1024 kilobytes make up a megabyte, 1024MB equals a gigabyte, and 1024GB equals one terabyte. We can't go much higher than a terabyte right now, but we may make larger hard drives in the future.
A cluster is the smallest unit of space used to store a file.
cluster
The smallest storage access unit on an IDE hard drive is a sector.
Maybe you should check your book. <---- not very nice A Cluster
SECTOR!
bytes
A cluster is the smallest unit of disk space that can be allocated to a file
Minutes is a unit of time GB is a unit of space on a hard drive
It all depends on how your disk is formatted.
Sector
Cell
Hard Drive Disk (HDD)