Did you know you can improve the overall performance of your network-attached storage (NAS) by installing an SSD? This isn't to expand the storage capacity of the NAS but to allow the OS to use the drive to cache frequently accessed data. It's a similar principle to RAM but albeit much slower. Still, using SSD caching could improve performance, especially when relying on slower SATA mechanical hard drives. I'll go into SSD caching, how to improve your NAS with an old SSD, and whether you actually need to do so.

What is NAS SSD caching?

Just like your desktop PC and smartphone, a NAS will use RAM to store data for quick access. This can be the OS, apps, services, or even stored data. An issue may arise when you run low on system memory, especially on NAS models with a set limit due to the selected processor. Running out of RAM can cause issues relating to performance, which can largely be alleviated through the use of SSD caching. You can think of SSD caching as a slower version of RAM, dedicating storage drives for the OS to store data for quick access. SSD caching can also help boost the performance of mechanical drives.

If you need faster speeds than what SATA hard drives can offer, this is where SSD caching can provide some benefits. Although this will increase the overall cost of your system, especially with larger and faster SSDs, caching using these drives will be more cost-effective than an all-SSD NAS, provide write cache benefits, is easy to set up and manage, and is great for accessing lots of smaller files, which is what you'll likely use the NAS for.

How to use an old SSD for caching

To use an old SSD for data caching inside a NAS, you'll need a spare SSD you no longer require and ... a compatible NAS. Not all prebuilt turnkey NAS models support the use of SSD caching, so you'll need to check the specifications sheet or manual for further information. Generally speaking, so long as your NAS has an M.2 slot, you should be able to use an SSD for caching. The process of accessing the M.2 slot(s) inside the NAS will vary between brand and model, but they're typically located either inside the enclosure, requiring the system to be taken apart, or can be accessed through a dedicated bay underneath the enclosure.

It's good to back up all data stored on the SSD, even if you believe this to have already been completed. Having multiple copies of data is never a bad thing. Once you're good to go, simply install the SSD inside the NAS, using one of the available M.2 slots. Once the NAS has been booted up, the drive should be recognized by the OS and it can be used for storing data or caching, depending on NAS and software support. Configuring the NAS to use the drive for caching is just as quick as adding the drive to an existing storage pool.

Do you need SSD caching for your NAS?

Whether or not SSD caching makes sense for your NAS depends on the hardware you're using. You won't be able to use SSD caching if your NAS doesn't support this feature. This can vary depending on the brand and model, though if building your own NAS, you'll be able to utilize all available SSD slots for caching data. Before looking at SSD caching, however, I'd recommend fully populating your RAM slots and reaching the maximum system memory capacity. When moving to SSD caching, be sure to rely on M.2 slots instead of dedicating SATA slots to this feature, which can otherwise be used for storing data.