Secondary storage, also known as auxiliary storage and external storage, is a form of computer data storage used to store data not actively in use. It is usually non-volatile meaning that the data remains even when the power is turned off. Secondary storage is a key component of modern computers, providing a convenient means to store and access large amounts of data.
Unlike primary storage, which is typically random access memory (RAM), secondary storage is not directly addressable. Instead, computer programs must use device drivers and special software to access secondary storage devices. Typical types of secondary storage devices include hard disk drives (HDD), solid-state drives (SSD), optical discs (CD, DVD, Blu-ray Disc), and magnetic tape drives.
By comparison to primary storage, secondary storage devices often have higher capacities and lower cost per unit of data stored. Furthermore, secondary storage can store data for much longer periods of time, making it ideal for applications such as archiving or for backing up data important to the system.
Despite their convenience, they are slower and less reliable than primary storage. Therefore, they are typically not suitable for applications that require real-time response or access to frequently changing data.
Secondary storage is also one of the key components of an enterprise storage system, providing additional capacity in addition to the server’s onboard storage. This can be used to store critical data separate from the operating system, allowing for it to survive a system crash or failure, and it can be organized into a centralized repository. As well, it can be used to move data across multiple systems for sharing or further analysis.
