Summary

• SSDs are pricier than HDDs: The price per GB for SSDs at 1TB is around $0.14, much higher than $0.04 for HDDs.
• Limited storage capacity with SSDs: Drives for NAS only reach up to 8TB, making it expensive to scale storage.
• SSDs have data write limits: Endurance is measured in terabytes written, meaning heavy workloads could shorten lifespan.

Populating a NAS with either hard disk drives (HDDs) or solid-state drives (SSDs) is a decision that needs to be made for any enclosure. Even the most affordable NAS with 3.5-inch bays will take a 2.5-inch SSD. Should you use an SSD over an HDD for storing data on the LAN? There are advantages to using flash storage, including speed, power draw, and longer-lasting lifespan, but it's not all good news for SSDs inside NAS. I'll run through a few reasons why you shouldn't.

1 SSDs are more expensive than HDDs

Price per GB

The price per GB of capacity is useful for working out storage costs. A typical lower-capacity HDD will cost around $0.04 per GB for 1TB. The higher the capacity, the lower the overall cost of storing data, even if the drive will be pricier. An SSD will set you back around $0.14 per GB at 1TB. Although one will save compared to the cost of cloud storage subscriptions, the cost of SSDs will quickly eat into your budget, surpassing the cost of the NAS device. It is possible to save by using SSDs designed for a laptop or desktop PC but this isn't recommended due to endurance concerns.

The drives aren't designed for NAS. NAS-specific SSDs, like their HDD equivalents, cost a premium compared to normal drives with the 4TB Western Digital Red 2.5-inch drive costing $310. That's $0.08 per GB and a full $0.05 per GB higher than a 4TB NAS HDD.

2 You can't store as much data on SSDs

The more the merrier

I've already touched on the limited capacities of SSDs and the same goes for drives built for NAS and server use. You will struggle to locate an SSD with a capacity higher than 4TB. The Samsung 870 QVO is one such SSD with a maximum capacity of 8TB, but it costs $570 for the luxury. Using four of these for a maximum of 32TB of storage space would cost more than $2,000 before factoring in NAS hardware costs. There aren't any NAS-specific SSDs with an 8TB capacity or higher. You'll need hard drives to store as much data on a single NAS as possible.

3 SSDs have a data write limit

Not the best for heavy workloads

No drive lasts forever and that includes an SSD. Unlike a mechanical drive with spinning platters and a motor, no moving parts are inside a solid-state drive. So how does an SSD eventually fail? It's all down to how data is stored. Using the power of electricity and memory chips, data is written and read to data banks on the PCB. The chemicals inside these chips will wear down as data is written to the drive. That's not to say an SSD will fail prematurely compared to an HDD, but if it's used to write lots of data, its lifespan will be cut dramatically.

This is why an SSD endurance is measured in terabytes written (TBW). An SSD with an endurance rating of 400 TBW can have 400 TB written to the drive before the capacity and/or performance takes a hit. If you don't have a lot of data to write to a NAS and want a drive that will last a long time, an SSD would make sense, so long as you don't mind paying a premium.