Secondary storage technology refers to storage devices and storage media that are not always directly accessible by a computer. This differs from primary storage technology, such as an internal hard drive, which is constantly available.
Examples of secondary storage devices include external hard drives, USB flash drives, and tape drives. These devices must be connected to a computer's external I/O ports in order to be accessed by the system. They may or may not require their own power supply.
Examples of secondary storage media include recordable CDs and DVDs, floppy disks, and removable disks, such as Zip disks and Jaz disks. Each one of these types of media must be inserted into the appropriate drive in order to be read by the computer. While floppy disks and removable disks are rarely used anymore, CDs and DVDs are still a popular way to save and transfer data.
Because secondary storage technology is not always accessible by a computer, it is commonly used for archival and backup purposes. If a computer stops functioning, a secondary storage device may be used to restore a recent backup to a new system. Therefore, if you use a secondary storage device to backup your data, make sure you run frequent backups and test the data on a regular basis.