In this definition, primary devices refer to the computer's main storage device, such as an IDE or SCSI hard drive. Secondary devices, under this definition, are any non-primary storage device, such as a tape drive, writeable CD-ROMs or removable flash drives.
Each type of storage media has different applications. Hard drives are the best choice for large volume, primary data storage. Regardless of the hard drive technology, the hard drive sacrifices speed for storage capacity and density when compared to volatile storage devices such as RAM (Random Access Memory) . RAM, on the other hand, is not typically used for file system data storage because of its non-permanent nature. Due to its high-speed connection to the computer's CPU, RAM makes the best choice for primary storage. RAM typically can store and retrieve data at speeds that exceed 4 to 5 times that of the fastest hard drives.
Writeable CD-ROM media, tape drives and flash drives make good choices for secondary storage devices (using either definition). These devices are often removable and, with the exception of magnetic tapes, offer higher reliability than hard drives that are dependent on moving parts. Computer users often depend on these devices to store backup or archive information, or to carry data that must be easily portable from site-to-site.
"A character file may be transferred to a host for one of three purposes: for printing, for ...