Secondary storage is nonvolatile. Writing is the process of saving information to secondary storage devices. Reading is the process of accessing information from secondary storage devices such as: Hard disk - Internal hard disk, hard-disk cartridges and hard-disk packs Optical disks - CD, DVD, and DataPlay are types of optical disks Specialized storage devices - solid-state storage, Internet hard drive, magnetic tape, microfilm and microfiche. Hard Disks You are likely aware that the computers you use have a hard disk drive in them. These drives do not have one circular piece of plastic like old floppy disks had. They are made up of a series of disks or cylinders.
A typical desktop machine will have a hard disk with a capacity of between 100 gigabytes up to 1 terabyte .
There are two ways to measure the performance of a hard disk: