What Is a Storage Device?
A storage device is a hardware unit that holds electronic data, allowing it to be accessed easily by applications and end users. Often called a disk or drive, a storage device is usually an external machine connected to a computer through a cloud hosting provider or plugged in directly to a USB port. It can also be a permanent component incorporated into a PC or laptop.
Storage devices evolved from earlier physical forms of data storage, such as punch cards and paper tapes with sequential holes that can be read by computer. Today’s storage devices are typically external hard disk drives (HDD) or solid-state devices.
A hard disk storage device or hard disk drive contains a flat spinning disc or platter coated with a magnetic material. The drive adds, deletes, or alters data through a read-write head resembling the needle on a record turntable.
Solid state storage devices take the form of solid state drives (SSD), flash drives (also called thumb drives or USB sticks), and even smaller SD cards.
All of these allow large volumes of data to be stored on memory chips or magnetic platters densely packed with information.
Key Takeaways
- Storage devices are digital data repositories that allow files to be saved, accessed, and altered quickly and conveniently.
- There are two different types: primary storage devices that provide PCs with cache and random access memory (RAM), and secondary storage devices like hard disks and flash drives.
- In most cases, the term storage device refers to the second type: a separate hardware unit for storing large volumes of data.
- Secondary storage devices include hard disk drives, solid state drives (SDD), and other solid state formats like flash/thumb drives and SD cards.
- The use cases for each type of storage device can differ based on requirements for capacity, speed, price, and portability.
Types of Computer Storage Devices
Computer storage can be divided into two main categories: primary storage and secondary storage. These are sometimes referred to as volatile and non-volatile storage:
The main focus of this definition is secondary (non-volatile) storage devices.
Features of a Storage Device
Experts define the value of storage devices according to four key metrics:
- Capacity, or the physical volume of data the device can store. This is usually listed in gigabytes (GB) or terabytes (TB).
- Speed, or the pace at which a storage device can save, retrieve, or alter data.
- Durability, or the physical sturdiness of the device or its storage media.
- Portability, or how easily it is to move or relocate the device.
How Computer Storage Devices Work
In a hard disk drive, the drive’s read-write head moves up, down and sideways across the physical disk, writing data magnetically to specific coordinates that correspond to each data point.
Unlike hard disk drives, solid state storage devices have no moving parts. Data is stored electronically on memory chips which enable faster retrieval and alteration.
Other Types of Computer Storage
Data can also be stored on optical storage ‘devices’ such as CDs, DVDs, and Blu-ray discs (BD). However, these are more accurately described as types of storage media since they have no built-in computing capabilities of their own. They are typically used to store entertainment media – music files, films and other video files, as well as high-definition Blu-ray format films.
Corporate data is often archived or backed up to magnetic storage arrays. Magnetic tapes can also provide a durable medium for long-term data storage, however they aren’t suitable for fast retrieval and continual access by multiple end users and applications.
Storage Device Use Cases
HDDs and SDDs are best suited when hundreds of gigabytes (GB) or multiple terabytes (TB) of storage are needed for local use. They can be installed inside PCs and laptops as a permanent form of secondary storage for frequently accessed files. They are also available as external devices that can be connected by USB cable when additional large volumes of data storage are required.
Thumb drives and SD cards can also be used to store large volumes of data, though usually in increments of 100 gb or less. Because they are physically small, light, and portable, they are perfect when you need to access files quickly on more than one device.
Storage Devices Pros and Cons
Storage Device Type | Pros | Cons |
---|---|---|
Hard disk drives | Capable of large storage volumes, less costly than SDDs, long lifespan. | Slower read-write speeds, more damaged thanks to moving parts, physically larger and heavier than other formats. |
Solid state drives | Faster read-write and data retrieval speeds, no moving parts so less prone to damage, smaller and lighter than HDDs. | More expensive with a higher average cost per gigabyte, somewhat shorter lifespan versus HDDs. |
USB, flash or ‘thumb’ drives | Small, light, highly portable storage. Easy to use with faster data retrieval than optical discs | Smaller storage volume versus HDDs and SSDs. Durable but small size means they can be easily misplaced. |
SD cards | Extremely light and portable, can be in many different devices, fast data retrieval speeds. | Storage capacity can be limited depending on the data format used. Also easily lost or damaged. |
Optical disc formats | Good for inexpensive, long-term data storage of personal files. | Storage capacity is much smaller than secondary storage device options. Easily damaged. Data retrieval much slower than other options. |
The Bottom Line
By definition, storage devices are temporary digital vaults that keep important files and information accessible and protected. As the volumes of personal and business data continue to grow and grow each year, having fast, high-volume storage devices to choose from is essential.
In recent years, PC, smartphone and tablet manufacturers have moved increasingly to solid state devices for built-in secondary storage. There is still strong demand, however, for HDDs, which provide a cost effective and fast-enough storage device option when additional capacity is required.