Tech Insight : A Quick Guide To Flash Drives & HDD Storage

In this brief guide to storage technology, we compare and contrast the benefits of flash drives and Hard Disk Drives (HDD) for enterprise storage and take a look at some other popular storage options.

What are Flash Drives? 

Flash drives, sometimes called Solid State Drives (SSDs), use ‘flash memory’ to store data. The flash memory (where the data is stored) is integrated circuits, i.e. an array of memory cells made from floating-gate transistors that hold the data when the drive isn’t powered. Unlike traditional hard drives, they don’t have moving parts and offer faster data access and increased reliability. Their compact size also makes them an ideal choice for devices such as laptops and mobile devices. Popular types include USB flash drives, SSDs for computers and servers for high-speed data access, and memory cards such as the type commonly used in cameras and mobile devices for lightweight, mobile storage.

Flash Storage in Business Use 

Businesses use flash storage for tasks requiring speed and efficiency, such as operating system installations, running applications, and data processing.

Enterprise flash storage, commonly found in enterprise-level datacentres, is a sophisticated solution designed for handling large-scale data storage needs in datacentres. In terms of its aggregated capacity, it can run from tens of terabytes (TB) to many petabytes (PB) – where a petabyte is one quadrillion bytes! It consists of multiple flash drives assembled in a rack-mounted array.  The system is operated and governed by controller hardware, i.e. a computer that handles the input/output from hosts to the storage. The controller also performs other advanced functions to help maintain optimal performance.

The Benefits 

Enterprise storage of this kind offers benefits like:

– High performance – superior speed and low latency, significantly enhancing performance for demanding applications.

– Reliability and efficiency. With no moving parts, flash drives are more reliable and consume less power compared to traditional hard disk drives (HDDs).

– Scalability. The modular nature allows for easy expansion to meet growing data needs.

What Is QLC Flash Storage? 

QLC (Quad-Level Cell) flash storage is the latest advanced technology where each memory cell stores four bits of data (hence the ‘quad’ part of the name). This design allows for higher storage density, enabling more data to be stored in less physical space. As a result, QLC offers a cost-effective solution for businesses, particularly effective for managing large volumes of unstructured data.

While QLC increases storage capacity and reduces cost per GB, it also presents challenges around endurance. However, ongoing advancements are addressing these issues, making QLC a promising option for businesses seeking efficient and economical data storage solutions.

What About NVMe Flash? 

Another flavour of business flash storage is NVMe (Non-Volatile Memory Express). This is essentially a protocol tailored for flash storage, that can deliver significant performance improvements over older HDD-oriented protocols like SATA and SAS. It works by optimising data queues and buffers specifically for flash memory, which leads to faster data access and transfer speeds.

Some of the key benefits of NMVe include:

– It’s fast. NVMe greatly accelerates data processing and access, crucial for applications needing quick data retrieval.

– It offers expanded connectivity. NVMe-over-fabrics technology enables high-speed connections across datacentre networks, thereby supporting scalability.

– It’s future-ready. Using NVMe enables businesses to leverage the latest in flash storage technology for efficiency and growth.

Hard Disk Drives (HDD) Explained 

Hard Disk Drives (HDDs), like the type found in desktop computers, store data on spinning magnetic disks. They offer larger storage capacities at a lower cost per GB compared to flash drives. This makes them suitable for storing vast amounts of data like archives and backups.

For enterprise storage, HDD rack-mounted arrays preceded flash storage arrays and are still widely used as pooled storage for multiple enterprise users.

Comparing HDDs and Flash Drives for Enterprise Storage

Here’s a quick and easy comparison between the advantages and disadvantages of flash storage compared to HDD in terms of performance, cost, reliability, and future-readiness.


Flash storage, such as SSDs, significantly outperforms HDDs in speed. They offer lower latency, with access times in low milliseconds or even microseconds, compared to the multiple milliseconds of HDDs. This results in much higher input/output operations per second (IOPS) and throughput rates up to four or five times quicker than HDDs. The lack of moving parts in flash drives contributes to this rapid performance.

HDDs, however, are limited by their mechanical nature, i.e. the physical movement of the moving parts (spinning platters and read/write heads) results in slower access times and reduced IOPS compared to flash storage.


In terms of cost, flash drives are historically more expensive per GB than HDDs, although the cost of flash storage has been decreasing. For example, as of October 2023, the cost averaged $0.075/GB. While still more costly, the price gap between flash and HDD is narrowing. For example, again in OCtober 2023, SAS HDDs averaged $0.05/GB, and SATA HDDs were even lower at $0.035/GB.


Solid State Drives (SSDs) are generally more reliable than HDDs due to the lack of moving parts, which makes them less susceptible to mechanical failures and physical shocks. The mechanical components in HDDs can also be more prone to wear and tear over time, potentially leading to higher failure rates compared to SSDs.


With their superior speed and decreasing costs, flash drives are increasingly becoming the preferred choice for future-focused enterprise storage, offering scalability and efficiency for high-performance computing environments.

While HDDs still play a role in enterprise storage (especially for archival and low-cost, high-capacity storage needs), they may not be as well-suited for future high-speed, data-intensive applications as flash drives.

What About In the Cloud? 

Flash storage is ideal for cloud applications requiring high performance, such as databases (e.g. SQL, Oracle, SAP Hana) and computing environments with specific needs (e.g. Windows, Lustre, MacOS). It’s chosen for its speed, lower latency, and high IOPS (Input/Output Operations Per Second). For example, major cloud providers like Amazon Web Services (AWS), Microsoft Azure, and Google Cloud Platform (GCP) offer solid-state storage options with varying levels of performance and cost. Customers can select service levels based on capacity and IOPS, tailored to their specific workload requirements. There are also specialised flash storage options for file storage and offerings from specific suppliers (e.g. Azure’s NetApp Files).

HDD storage in the cloud, however, is mainly suitable for data that doesn’t require the high-speed access of flash storage. It’s often used for bulk storage, backups, archives, and other less performance-sensitive applications where cost is a more significant factor than speed. As such, cloud HDD storage is generally offered with service levels focused on capacity rather than speed. Customers can choose HDD storage for cost-effective, large-scale data storage needs and cloud providers may automatically use HDDs for certain types of storage services, particularly where high capacity at a lower cost is more important than performance.

All-Flash Datacentres? 

An all-flash datacentre is a concept where traditional storage media like HDDs and tapes are entirely replaced by flash storage. This idea has been gaining traction for about a decade, driven by the decreasing cost of flash storage (e.g. QLC flash) and its advantages in terms of rapid data access.

All-flash datacentres are an attractive proposition because flash storage’s rapid access speeds are particularly beneficial for tasks like running analytics on large datasets, where quick data retrieval is essential. Also, with flash storage, there is the potential to leverage artificial intelligence (AI) on extensive datasets, extracting more value from the data. In scenarios like ransomware attacks, the ability to quickly recover data from flash media may also prove to be a significant advantage.

Arrival and Challenges

The transition to all-flash datacentres is ongoing but gradual. While suppliers of flash storage are optimistic, analysts suggest that flash will penetrate secondary workloads but won’t completely replace spinning disks in the near future. As of now, a sizeable portion of data is still stored on HDDs.

One major challenge to the introduction of all-flash datacentres is the current lack of flash capacity to fully replace HDD storage. Also, despite falling prices, the cost of flash storage is still a consideration, especially for vast data storage requirements where HDDs can be more cost-effective.  It’s also worth remembering that certain types of data and use cases may still benefit from the characteristics of traditional HDD storage, delaying the complete shift to all-flash solutions.

Other Enterprise Storage Solutions 

A few examples of other enterprise data solutions include:

– Network Attached Storage (NAS). This refers to a network-connected device providing centralised data access to multiple users.

– Cloud Storage. Clearly, this online storage method (which incorporates flash and HDD) is the one that most businesses would recognise. Cloud services offer a range of benefits including cost-effectiveness, ease of use, scalability, remote access, and often enhanced security features.

– Hybrid Storage Systems that combine the speed of SSDs with the capacity of HDDs can be a way to offer a balanced solution.

What Does This Mean For Your Business? 

In today’s data-driven world, understanding your business’s unique storage requirements is key to selecting the right technology. The choice between flash drives and HDDs isn’t just about current requirements but also about anticipating future needs. Flash drives, with their high performance and reliability, are ideal for operations demanding speed and frequent data access, whereas HDDs are still relevant for large-scale storage where cost-effectiveness is paramount.

Cost is always a major concern for businesses and while flash storage costs are decreasing, they are still higher than HDDs and it may be a case of balancing the need for speed and performance against budget constraints. The narrowing price gap, however, may now be making flash a more accessible option for a broader range of applications.

As stated above, the reliability of SSDs (due to their lack of moving parts) could offer peace of mind for businesses with critical data needs. Also, as technology moves towards faster and more data-intensive applications, SSDs are a future-ready choice, ensuring your business remains competitive and agile.

With cloud storage becoming a staple for many businesses, understanding the use of flash and HDD in the cloud is helpful. For example, flash is ideal for performance-hungry applications in the cloud, while HDDs serve well for less demanding, bulk storage tasks. This distinction can help guide businesses in optimising cloud storage expenses and performance.

Looking ahead, the concept of all-flash datacentres, while still developing, points to a future where rapid data access and processing will be standard. Businesses should monitor this trend, as it promises enhanced capabilities for data analytics and AI, alongside quicker recovery from data incidents.

Finally, many enterprises may want to consider a more holistic approach to data storage, possibly employing hybrid storage systems that combine the speed of SSDs with the high capacity of HDDs. This strategy allows businesses to leverage the best of both worlds, ensuring a balanced, efficient, and scalable storage infrastructure.

Hopefully, this brief guide has gone some way to demystifying some aspects of enterprise storage technologies.