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Which Synology NAS should you buy? Model numbers explained

What do those Synology model numbers mean? We run through Synology’s range and explain the differences between its models.

Synology is one of the most popular network storage companies around, with its wares available throughout the UK.

For consumers, this is excellent news when it comes to ease of buying. However, the company’s range is huge, which makes picking the correct NAS for your needs a little tricky. There are more than 30 models listed on the company’s website, with cryptic names such as RS3617xs+ and DS216+II. So where’s a prospective buyer to start?

Related: Synology DS216 review

What shape NAS?

Synology makes two basic NAS shapes: rack-mounted and desktop. In this article, we’re going to cover only the kind of desktop NAS you’d use in your home or a small office, rather than anything that requires a server rack.

Your first decision will concern the number of drive bays: do you need one, two, four or more? A one-bay NAS is useful for sharing files around your home, but it shouldn’t be your only backup – if the disk becomes corrupt, you’ll lose everything. A two-bay NAS, when formatted with Synology Hybrid Raid (SHR), provides data security by duplicating one disk to another, at the expense of one disk’s capacity.

Things become more clever as you move up to a four-bay NAS or larger. When fitted with three or more disks, a Synology NAS will be able to tolerate one disk failing without the loss of any data – and all you sacrifice is the capacity of a single hard disk.

A neat way to visualise this is to use the tool on Synology’s website, which will also explain what will happen if you use a different RAID type from SHR, such as RAID0 or 5.

Synology NAS model names explained

On first look the array of Synology NAS devices and model names may appear bewildering. When it comes to home or small-business use, however, you need only concern yourself with models that have the “DS” prefix. This stands for DiskStation, and is the upright desktop box . The following matrix breaks down a Synology model name into its component parts.

Model example


Number means


Suffix means



Four bays, 2016 model

Standard mid-range model, more powerful than ‘j’ range



Two bays, 2016 model


Powerful processor, hardware encryption for video transcoding



Two bays, 2016 model


Cheaper home model, slower processor



Two bays, 2016 model


Super-budget model, single-core processor, small amount of RAM



Two bays, 2016 model


Intel-powered NAS. Designed to fill a niche between DS216 and expensive business models



Two bays, 2016 model


Same as above, with newer processor (as previous processor discontinued)

Model numbers

After DS prefix comes the model number. Most of the time, the first number denotes how many drive bays are in the NAS. This works for models such as the DS116 (one drive bay) and DS216 and DS416 – but you’ll occasionally come across a model that doesn’t fit this format – the DS1515, for example, has five bays.

The last two numbers represent the model range. Synology tends to change this each year with its range refresh, so in the past few years we’ve had DS212, DS213, DS214 and DS215, for example.

Processor speeds have increased through the generations, so the latest DS216 is far faster than the DS212, leading to an increase in interface smoothness, transfer speeds and video-transcoding performance.


There are also a few suffixes scattered about. The easiest to explain is “j”. A NAS with this suffix – such as the DS216j – is a budget, home-orientated model with a slower processor and often less RAM than more expensive versions.

As mentioned above, this can have a significant impact on how quickly the NAS can transfer files over your network. At the other end of the home-orientated spectrum are the “play” models, such as the DS216play. These are designed to stream video over your network, and so have powerful transcoding engines to convert video on-the-fly into a format and resolution playable by the target device, whether it’s a tablet or a PC.

There are a couple of extra suffixes too. Synology sometimes upgrades a NAS with a faster processor and more RAM, but without changing the model number. In these cases, Synology adds a “+” suffix. There’s also a +II model, the DS216+II, which is identical to the DS216+ but has a newer processor, as Intel discontinued the old chip.

Finally, Synology makes a super-cheap “se” version of the two-bay DS216. This is around £40 cheaper than the DS216j, but it has only a single-core 800MHz processor and 256MB rather than 512MB of RAM. In addition, it has only a USB 2 rather than USB 3 port for an external storage device – so appears to be a false-economy overall.

Note that Synology’s NAS specifications don’t always fit the format as neatly as described above: for example, a four-bay DS416 has a different processor to a DS216. However, the suffix and model number rules of thumb still apply.

Disk or no disk?

Resellers such as sell Synology NAS boxes, both with and without hard disks installed. The supplied disks tend to be WD Red models, which are designed to be used specifically with a NAS.

We’ve found that there’s little difference in price between buying a NAS with preinstalled disks and buying the NAS and disks separately, so if you can find a model with the right capacity disks already installed, then that would be the best option to buy.

However, it’s always worth doing the maths – a special offer on a separate hard disk might save you some cash; and fitting a hard disk in a Synology NAS takes no time at all.

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