What is the main purpose of a secondary storage device? Simply put, it's computer hardware that stores data until it's explicitly deleted or overwritten. This is in contrast with primary storage, such as random access memory, that stores data only as long as it's receiving power. Functions of secondary storage include storing data that will be kept indefinitely, backing up data in case of device failure and transmitting data from one place to another. The functions of a storage device often determine what type of device will be used, depending on the main purpose of the secondary storage device.
Hard Drives and SSDs
Some of the most common secondary storage devices are magnetic hard drives – long used in laptop and desktop computers. They use magnetic heads to store and read data on spinning metal disks known as platters. They're generally the first place used to store data on a computer, from the operating system and other applications themselves to files you create on the machine.
More recently, computer manufacturers have started to ship more devices with what are called solid state drives, or SSDs. SSDs don't have moving parts like spinning platters. Instead, they use flash memory, similar to USB flash drives. They're usually faster and less noisy than hard drives, but they can be more expensive for the same amount of data storage, so both devices are still currently in use for different applications.
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Some forms of secondary storage are commonly used because they're portable. USB flash drives are a common modern example, and earlier examples include floppy disks, ZIP disks and some that are still in use, such as compact discs, or CDs, and digital versatile discs, or DVDs.
These pieces of equipment are often used to transfer files from one place to another or to distribute recorded media like music and movies. They can also be used to back up files stored on hard drives and SSDs since they're easy to transfer to another computer.
One risk with secondary storage used with multiple devices is that it can transmit malware from one computer to another.
For backing up and storing large amounts of data, organizations often turn to magnetic tape. Similar to cassette tapes used for music and VHS tapes for movies, magnetic tape drives can store large amounts of data in a small amount of space at little cost.
Tape has been used for many years, so tape drives have a long history behind them and are known to be reliable and durable, often lasting longer than disks. They're usually slower than disks or SSDs, though, so they're less suited to use with data that requires regular, fast access.