The Great Debate: SSD vs. HDD. What’s the Difference and What Makes Sense for Your Use Case
SSDs vs. HDDs. It’s a raging debate within the IT world. Some folks swear that the performance of SSDs so vastly outperforms HDDs that the higher cost is unquestionably worth it. Others feel that HDDs offer decent-enough data transfer speeds at a much better price. The truth depends on your scenario and where you want to put your dollars!
This blog post will cover the basics of HDDs and SSDs and offer some guidance and options on what makes the most sense for your use case.
SSD vs. HDD. The Basics and a High-Level Comparison
For those new to the world of servers and computer hardware, here is a quick primer on the main differences between these two storage mediums.
HDDs (Hard Disk Drives, for those keeping acronym-score at home) read and write data by spinning a magnetic disk. The faster the disk spins, the quicker the data is accessed. This technology has been around for several decades now, and HDDs are an extremely tried and true storage medium. And while disk manufacturers have perfected their techniques to make HDDs extremely reliable (and large; more on that later), the main downside to HDDs are the limits at which they can read & write data. Additionally, the mechanical moving parts generate a significant amount of heat in the drive and, consequently, the computer.
SSDs (Solid State Drive) are a storage medium based on Flash technology. Whereas HDDs have a spinning disk, SSDs comprise millions of memory cells that can flip between binary states to store their data (those little USB thumb drives utilize the same technology). Because SSDs access data without the need of a physically moving platter, they offer the significant advantage of much higher read & write speeds and generate much less heat than their HDDs counterparts.
It seems then like SSDs are a no-brainer…
Not so fast. Because HDDs have been in production for decades, the technology has had more time to be improved. HDDs offer two significant advantages:
- Cost. While SSDs have been dramatically falling in price over the past couple of years, there is still a higher per GB cost for an SSD than HDD. As of this writing, a 1TB HDD is approximately $50, while an SSD of the same volume is about twice that (other factors can impact the price, such as the form factor of the drive).
- Volume. Most HDDs offer volumes that are not commercially available as SSDs (yet). That price difference compounds the larger the drive. For example, Western Digital manufacturers an 18TB drive which retails between $320 and $380. Assuming you can find it, anything close to that in an SSD will be in the thousands.
TECH FOOTNOTE – NVME SSDs: Most SSDs, especially in the laptop and desktop market, come in an M.2 form factor with an NVMe interface. NVMe SSDs have a much higher data transfer rate compared to SATA and SAS drives. We are starting to see more NVMe bays for Enterprise servers in the Dell 14th Gen and HPE 10th Gen models. Previous models are almost all exclusively SATA or SAS connectors for SSDs.
Which Makes the Most Sense for My Use Case?
Keep these simple guidelines in mind:
- SSDs will always outperform HDDs. If you have the budget for it, go with SSDs.
- The exception could be a file server or JBOD where you need to take the machine’s storage to its max. SSDs are not feasible when you get into the higher TB drive volumes.
- Go with HDDs (or at least SAS HDDs) if you are budget-conscious. SAS drives are faster and more reliable than their SATA cousins. And if you go the refurbished route, that price difference between SAS and SATA diminishes.
- Don’t forget! You can mix SSDs and HDDs in the same server. A typical configuration is to install the server’s OS on an SSD and then use HDDs for storage. Just remember to follow guidelines for RAID – mixing and matching of drive types is forbidden.
As hard drive technology continues to change and improve, we are sure to have many more great debates on what kind of storage is best for your server. With key principles in mind, you can make an informed decision.
Have a question or a different take? Leave a comment below! We love hearing from our readers!