If you need to equip your NAS with more hard drives but have already filled up every drive bay, there are ways to do this without buying a new one. Most of the solutions are less than ideal, but they’re cheaper than blowing a hole in your wallet on a new NAS and are relatively straightforward to implement.

Expand storage with external USB HDD enclosures or drive bays

Not great but affordable

Credit: Ismar Hrnjicevic / How-To Geek

The quick, cheap, and dirty way to expand your NAS storage space is to plug an external HDD enclosure or a multi-bay drive enclosure into your NAS. Many NAS devices come with at least 5Gbps USB ports, which should be enough even for multiple HDDs.

While cheap and simple to implement, this storage expansion method leaves a lot to be desired. The most obvious downsides include bandwidth throttling and high latency, especially if you use USB 2.0 ports. But even if you use faster USB ports, you can still run into bottlenecks if you opt for an enclosure that can house more than a few HDDs.

But low bandwidth is just one concern. There’s a good chance your NAS won’t play nice with external storage enclosures: you might get faulty drive reports on a regular basis, the enclosure might disconnect at random, and you might encounter sleep and wake problems if your NAS isn’t running 24/7. On top of that, many NAS systems can’t add drives connected via USB to RAID and ZFS pools, and even when they can, it’s best to avoid doing so since USB storage is much less reliable than internal drives.

Compatible Devices

3.5 inch SATA HDD or SSD up to 20TB

Brand

ORICO

A good, easy-to-assemble USB 3 hard drive enclosure.

Get a 5.25-inch to 2.5-inch or 3.5-inch HDD disk bay

A solid choice, but not many prebuilt NAS devices come with a 5.25-inch bay

Credit: ICY DOCK

If your NAS comes with a 5.25-inch drive bay, you can slot an HDD cage into it and directly connect it to the NAS via SATA or SAS. 2.5-inch adapters can usually hold four or six drives, while most 5.25-inch to 3.5-inch adapters can fit three 3.5-inch HDDs.

The good news is that internal disk bays are affordable and that your NAS should work great with one, but the bad news is that you need a 5.25-inch slot on your NAS for this to work, which is a rare sight nowadays, at least on prebuilt solutions.

If your NAS has one or more of these bays, this is probably the best way to expand storage because you can connect HDDs via SATA or SAS directly to your NAS, add extra HDDs to RAID, avoid performance or reliability issues, and properly cool the drives.

Storage Capacity

8TB

Compatible Devices

SATA

Brand

Western Digital

Spindle speed

5640 RPM

Transfer rate

Up to 215 MB/s

Workload

180TB/yr

The WD Red Plus hard drive line is designed specifically for NAS usage. This means the drive is build to withstand 24/7/365 usage, with up to a 180 TB per year workload rate. You’ll also get a 3-year warranty with the purchase of WD’s Red Plus drive lineup.

Get a DAS and connect it to your NAS

Or create a DIY DAS

Credit: Lucas Gouveia / Hannah Stryker / How-To Geek

Plugging a DAS into your NAS is the best way to add more HDDs to your current setup if your NAS enclosure doesn’t have a 5.25-inch drive bay. While you might find a consumer DAS system that uses SAS connections, a huge majority of offerings use USB connectivity. That said, you should aim for a SAS-based DAS if possible because they offer excellent reliability, low latency, and high bandwidth. There are relatively affordable used server-grade SAS DAS options on eBay, and HBA SAS cards only cost a couple of dozens of bucks.

If you’re feeling adventurous and don’t mind getting your hands dirty, you can create your own DAS, which can be a better solution than buying a prebuilt one because you can use a case with a ton of HDD bays, spend less cash, and still get all the benefits of using a prebuilt DAS.

For this venture, you’ll need a case along with a power supply, an SAS HBA card, some cables, and some free time for research, hunting down parts, and assembling the thing. The advantage of going the DIY route is that you can use any case you like, including server enclosures that can fit more than a dozen HDDs. On the flip side, getting a ready-made, plug-and-play solution is a better choice if you don’t want to spend time building your own.

Lastly, you can also get an expansion unit if you own a prebuilt NAS that supports one. This is basically a DAS, but specifically made for prebuilt NAS systems. Vendors such as QNAP, Synology, and TerraMaster sell them. They’re very simple to manage, and you can find a decently priced one without much hassle.

Speed

375 MB/s

Weight

4.1 Pounds

You can use the QNAP TR-004 DAS as a standalone DAS system or connect it to your QNAP NAS and seamlessly expand its storage.

Connect a second NAS to the primary one over NFS

Not as good as adding a DAS

Plugging a DAS into your NAS is the best way to add more HDDs to it and expand your storage the right way. You can, however, also use a second NAS (if you already have one lying around) and connect it to the first one over NFS (Network File System). You’ll be able to access the secondary NAS through the main one, but you’ll still need to connect to it directly if you need high bandwidth. In general, this can work, but it comes with caveats.

The major one is that you aren’t creating a proper storage pool expansion; you’re just adding a separate storage pool that you can access through the main NAS. The two systems can communicate and send files between each other, but you won’t be able to add drives in the second NAS to your existing RAID array or ZFS pool.

You’ll also get worse performance, more management overhead, and more failure points than simply attaching a DAS to your primary NAS device.

Adding a DAS to your NAS is the best way to add more HDDs to it

At the end of the day, if you need to expand your NAS storage but don’t want to get a new unit with more drive bays and don’t have any 5.25-inch drive bays sitting idle, you should seriously consider choosing the DAS route, or getting an expansion unit if you own a prebuilt NAS.

Alternatively, consider switching to higher-capacity hard drives. Nowadays, you can get 8TB, 12TB, or larger hard drives for a reasonable amount of money, which can drastically expand your storage if you’re still using older drives with only a few terabytes of capacity.