When shopping for new storage drives, you can choose between a hard disk drive (HDD) and a solid-state drive (SSD). Both have advantages and drawbacks for storing data inside PCs, servers, network-attached storage (NAS), and other hardware. I needed to expand (and replace) my storage pool in my primary storage device, and I ended up opting for a few 16TB HDDs rather than moving into 2025 with an all-SSD array.

The SSD is the better option ... mostly

Faster speeds are met by higher prices

An SSD is my go-to recommendation for anyone looking for a boot drive or somewhere to stash local files on a desktop or laptop PC. It's also what I would typically use inside a server to run Docker containers, virtual machines (VMs), and build wacky systems for doing countless tasks, but when it comes to long-term storage, nothing beats the hard drive. Like many of my esteemed colleagues, I opt for mechanical drives to store lots of data.

But what if you're not planning to save too much data? An SSD (or a few) can make more sense. You'll see more hardware launches from NAS brands such as Asustor and Synology that focus on SSD storage, and that's because they can last longer when treated well compared to mechanical drives. An SSD has no moving parts and therefore only really has wear on the internal components through writing, due to how the technology works. The less you write to the drive, the longer it should last.

Other factors can affect the longevity of an SSD, of course. This includes heat, not having adequate cooling within the system, writing too much data to the drive (most SSDs will have endurance ratings), and unexpected power losses. An uninterruptible power supply (UPS) should almost always be present and connected if you're running NAS or building out a home lab. These can trigger hardware failures that could result in data loss.

Why buy HDDs over SSDs?

The primary reason for me and many others to continue purchasing hard drives is cost. These units are notably cheaper than SSD counterparts, with some models coming in at $0.02 per GB of storage space — and that's for server (or NAS) grade hardware too. Then there's capacity. SSDs have grown in size over the years, but you'll still need to spend the big bucks and pick up enterprise-grade storage to store any more than 8 TB of data per drive.

That's simply not the case with hard drives, which can be found in capacities ranging from just 1 TB to 24 TB for NAS. Picking up a 16 TB drive allows me to configure a RAID for local data protection without using all available drive bays. Going with larger drives also means the storage pool can be considerably larger when all bays are populated with drives, compared to using an array of 8 TB SSDs. There's also the case that you don't typically need SSD speeds.

A NAS or home server will have up to two 1Gb or 2.5Gb ports, which can be easily saturated with heavy file transfer requests and a mechanical drive. These bulky spinners may seem slow with just 550 MB/s compared to the fastest PCIe 5.0 NVMe SSDs, but that's more than enough for a 100 MB/s LAN connection. Even moving up to 10 Gb may not show much benefit moving from HDDs to SSDs, but this depends entirely on your LAN and how you use data.

For me, it makes more sense to stay with mechanical drives for now. And replacing drives in TrueNAS, which just so happens to be my primary storage NAS OS, is straightforward enough that larger HDDs can be rotated in without causing much fuss. That said, even if you're running premium drives and have a RAID configured, you should always consider following the 3-2-1 backup strategy to ensure you're adequately protected against data loss. Drives can fail ... even SSDs.

Noise and heat could be a factor in option against HDDs, especially when using multiple units inside devices near where you work. That's not the case for me since all my equipment is in racks inside the garage. It's handy since we don't need that room to be quiet, and there's ample airflow to aid with keeping all the systems cool.

I'll make the switch ... eventually

SSDs are the future, but there's also a case for HDDs. While technology continues to advance, we'll likely be at a point where more SSD capacities will be readily available for consumers, but we're not quite there yet. I'll happily make the switch to SSDs once capacities increase, endurance improves, and costs continue to fall. I can't justify more than $300 for an 8TB SSD when that same budget could fund multiple HDDs of the same size.