In the world of data storage, storage devices are divided into one of two categories based on how frequently an organisation needs to access that data: primary storage and secondary storage. In this article, we’ll take a closer look at these two categories as well as clear up some misconceptions around primary and secondary terminology.
What Is Primary Storage?
Primary storage, also known as main storage, refers broadly to the methods and technologies of storing data that must be accessed frequently. Primary storage includes both volatile primary memory, such as RAM and DRAM, and non-volatile storage media, such as storage-class memory, hybrid storage arrays, all-flash arrays (AFAs), and storage area networks (SANs).
According to Gartner, primary storage also includes persistent data storage for container environments and hybrid cloud IT operations that rely on a mix of cloud, on-premises, colocation, edge, and public cloud infrastructure.
Primary storage is all about supporting fast response times and input/output per second (IOPS)-sensitive structured data workloads. Business-critical applications, mission-critical data, as well as consolidation and support for virtual environments all rely on the fast and reliable response times of primary storage solutions.
What Is Secondary Storage?
Secondary storage, also known as auxiliary storage, refers to the storage methods and technologies used for the long-term storage of non-critical data that doesn’t need to be accessed as frequently as primary storage. The goal of secondary storage is to retain data until you overwrite or delete it, meaning it exclusively relies upon non-volatile storage media such as HDDs and SSDs. This is in contrast to primary storage, which includes both volatile and non-volatile storage media for quick access to frequently used data.
Primary Memory vs. Primary Storage
It’s important to note that depending on the industry, the terms primary memory and primary storage may be used interchangeably. This is especially true in consumer electronics, where storage conversations typically revolve around an individual computer’s use of primary memory like RAM vs. secondary storage devices like HDDs and SSDs.
On the scale of a computing device, volatile RAM may be considered the primary storage workhorse for storing the temporary memory needed by the CPU to process computing tasks, while non-volatile storage media like HDDs and SSDs will store your files and programs for long-term use even in the absence of power.
Scaled up to the data centre, however, the storage conversation shifts to expand the definition of primary storage to include non-volatile high throughput and performance storage systems such as all-flash arrays and SANs. This is to distinguish between the storage needed to house business-critical data, which must be accessed frequently while remaining non-volatile, and the slower second storage that may be used to store less-frequently accessed data such as archives.
Differences between Primary and Secondary Storage
The key differences between primary and secondary storage can be summarized as follows:
Speed of access: Primary storage, often directly connected to the computer's processor, boasts rapid data retrieval speeds. In contrast, secondary storage, designed for long-term storage, typically has slower access times.
Volatility vs. non-volatility: Primary storage may include volatile storage media, which means its data is lost when the system is powered down, and non-volatile storage media, which retains its data even when the power is off. Secondary storage is always non-volatile.
Capacity and storage space: While primary storage offers limited capacity designed for immediate data processing tasks, secondary storage provides vast space suitable for long-term data retention.
Applications: As mentioned, data in primary storage must be accessed frequently and is used for business and mission-critical applications. Secondary storage is typically optimised for capacity and cost over performance and is a popular choice for backups and archives.
Understanding these differences is pivotal for IT professionals and consumers alike, ensuring optimal system performance and efficient data management.
Conclusion
Navigating the intricacies of data storage can be daunting, but distinguishing between primary and secondary storage simplifies the journey. In this article, we took a deep dive into the nuances between primary and secondary storage. The primary difference between the two storage categories is how frequently you need to access their data. Organisations need both primary and secondary storage solutions to meet their data needs.
Looking for the best primary storage provider on the market? Read on to learn why Pure Storage has been named a Gartner® Magic Quadrant™ Leader in Primary Storage for 10 consecutive years.
