Primary vs. Secondary Storage: How do They Compare?

September 10th, 2019

Every day we interact with primary and secondary storage without being cognizant of it. Rarely, however, do most of us stop to consider their differences. But these differences are important because they affect how we interact with data, namely by what the two different storage types can do.

You may be more familiar with primary storage as it is commonly used as random access memory (RAM), the memory used by computers for running programs and their data. Data saved within this type of storage is temporary and ephemeral. With secondary storage, it’s that hard disk drive (HDD) in our computers, or the CDs and DVDs we use for entertainment purposes. Secondary storage data is permanent, and typically only “goes away” if it is deleted or destroyed.

When on the market for data center backup software, it’s important to differentiate between primary and secondary storage, and just where they fit in the grand scheme of your data protection strategy. In this blog post, we’ll address just what primary and secondary storage are and how they differ!

What is primary storage?

There are three main types of primary storage that every IT professional should know about: read-only memory, programmable read-only memory, and cache memory.

Another type of primary storage is read-only memory (ROM), both a non-volatile and permanent type of primary storage. ROM maintains its contents even if the unit loses its energy. You can’t alter the data, as it is read-only. ROM is a dependable type of storage, great for booting start commands and other crucial data. Like ROM, there is also programmable read-only memory, or PROM, which only allows data to be stored once. Like a blank CD-ROM, PROM does not come with information stored on a chip. But once you have written data to it, you can no longer alter or delete that information.

There is also cache memory, a temporary form of storage that computer programs call on for quicker access during operation. Since it is physically nearer than RAM, this is the first step in the processor’s search for directives. If it locates the necessary data here, the processor does not retrieve data from the

What is secondary storage?

Secondary storage is best for storing data permanently. Why? Because it is non-volatile and not directly accessed by a central processing unit, the opposite of primary storage. 

Secondary storage is often referred to as “auxiliary storage” as well. While it is slower than primary storage, it is one of the most valuable forms of storing data because of its long-term storage capabilities and impressive capacity. While 10GB of RAM is somewhat impressive, the latest computers have secondary storage (hard drives) with a terabyte of space. 

The most common type of secondary storage are hard drives. Hard drives are the poster child for secondary storage. Many computers bundle hard drives as internal storage media, but external hard drives are popular as well. Data security professionals will often generate redundant arrays from various hard disks to avoid data loss. Traditionally, data is backed up across multiple devices with multiple copies to ensure recovery is possible. But with cloud backup adoption on the rise, this is becoming less common due to the resources exhausted. 

Next up are CDs and DVDs, the most well-known variety of secondary storage. Yes, these aren’t just consumer products! They are the most well-known type of second storage after floppy disks, which in recent years have fallen out of favor as well. Despite innovations in data storage, CDs and DVDs maintain their popularity because of the speed at which they retrieve data, their growing capacity, and portability. 

Also popular as a traditional form of backup is magnetic tape. Tape lives inside cassettes and cartridges, able to store over a tetrabyte of data with the latest developments with this technology. Despite criticisms of its stability (tape degrades over time), tape is still an alternative for secondary storage and backup offered by many leading vendors in the industry. 

Primary vs. Secondary Storage Comparison Table

For our visual learners, we’ve created a handy (and dandy) comparison chart for comparing primary and secondary storage.

primary vs. secondary storage comparison table |

As our relationship with technology progresses, it’s increasingly important to make sure we have access to our data even in times of crisis. Potential data loss situations lurk everywhere, whether it’s dropping your phone in a toilet (hey, it happens) or bored hackers commandeering your servers and wiping your data.

According to a recent report by Evaluator Group, 57% of data center backup software buyers are looking to replace or upgrade their current solution within the next year. If you want to know more about the experiences of data center backup pros, check out reviews on data center backup software