Chapter 01 – Synology Hardware

Chapter 01 – Hardware

Deciphering the Model Numbers

With over 30 NAS models Synology’s product list can be daunting at first glance. But the model number will help you zero in on the models that will meet your needs.

The model numbers begin with two letters which identifies the type of NAS. Although there are several prefixes and suffixes used by Synology, they fall into four categories.

The model numbers begin with two letters which identifies the type of NAS. Although there are many prefixes in the table below, the vast majority of the models are DS and RS versions. The EDS, NVR and VS models are specialized models that are not a typical full-featured Synology NAS while the FS & RS models are targeted to enterprise needs. The DX, RX and RXD prefixes are for expansion units, not standalone NAS units. The RC prefix is new and identifies a NAS that’s designed to be part of a high-availability cluster. The model prefixes are summarized in the table below.

Synology NAS Prefixes
Prefix Description
DS DiskStation: designed to sit on a table or shelf. These models run the gamut from home to enterprise use.
RS RackStation: designed to fit into standard 19″ computer racks used in data centers. Generally these are more powerful than the comparable DS model with more technology and are more expensive.
FS RackStation designed to use high-performance flash drive (Flash Station).
EDS Embedded DiskStation: designed to be used in a harsh or specialized environment. There’s no internal drives and everything must be external. The DSM software is pre-installed. These are designed for cars, boats and other specialized or industrial environments.
VS This is a companion device for managing live feeds from security cameras. There’s no internal disk and it must be paired with a Synology NAS.
NVR Network Video Recorder: This is an all-in one hardware solution for Surveillance Station..
RC RackStation designed to serve as a node in a high-availability cluster. It must be paired with another RC to provide failover ability..
DX DiskStation Expansion Unit: expansion unit to add drives to the DS NAS model. These expansion units are designed to sit on a desk or shelf.
RX RackStation Expansion Unit: Expansion unit to add drives to the RS NAS models. These expansion units fit in a standard 19″ computer rack.
RXD High-availability cluster expansion unit. Used by the RC units..

After the prefix there are three to five numbers. These identify the maximum number of drives that the NAS can manage along with the model year. The last two numbers are always the model year. The number before the model year indicate the number of drives that the model can handle within DSM. The total number of drives doesn’t mean that the model has that many drive bays, many models support expansion units (DX and RX units) and this number includes the maximum number drives, including expansion units, that are supported.

Like cars, the model year starts updating before the actual calendar year. For example, the DS415+ is an update of the DS412+ and it was released mid-2014 and widely available that November. Unlike cars, Synology will not upgrade each model line each year.

Synology sometimes refers to the year identifier as the series. For example, the DS1511+ was often referred to as part of the “11-series”. Synology now uses “series” to group their NAS models into performance classes so it can be confusing at times. I’ve noticed that they now use the nomenclature of xYY, such as “x17 series” or x16 Series” when they refer to the model year. While the definition of “series” can vary, the meaning is usually easy to determine from the context.

After the numbers there’s a model performance class (a.k.a. series) identifier suffix. The table below lists the current suffixes and which performance series they fall into.

Synology NAS Suffixes
Class Suffix Description
J This is the entry level “budget” model for the series. Part of the J Series.
No Suffix These are the standard models for the series. Middle of the road in performance and price. Synology refers to these as the Value Series.
+ These are the high performance models for the series. Highest in price and performance. Synology considers these business models and refers to them as the Plus Series.
xs These are enterprise class models that have enterprise features and prices. Part of the FS & FX Series.
xs+ Also enterprise class models but with more power, features, and cost than their xs siblings. Part of the FS & FX Series.
RP This means the model has redundant power supplies. The model will include other class suffixes and is used in several *Plus* and FS & FX Series models.
play A specialized model that is enhanced for video streaming that is part of the Valueseries.
slim A specialized model that takes up less space but can only be used with 2.5\” drives. Part of the J Series.
se A low cost, entry level model. It is part of the J Series although It is less powerful than other models in the series.
air A model with a wireless card built in. It can be used to connect to the LAN, server as a wireless hotspot or as a router. This is not used in any current models although used DS213air models may be found.

The J Series

These are the lowest cost Disk Stations and targeted to those of us with limited needs that won’t stress the technology. There will be compromises with the J Series hardware but there can also be significant savings. These models are a good place to start to see if a Synology NAS is suitable for you.

Any hard drives used can be moved to higher performance models should you decide to upgrade the hardware..

The Value Series

Performance of the Value Series is a step above the J Series and below that of the Plus Series. While there may be some situations suitable for the Value Series I find that I typically end up recommending the J Series for those who are just starting with a NAS, have minimal requirements or extremely cost conscience, while the Plus Series is better suited for those who need more performance. While this series contains models that could be seen in enterprise business environments they are really designed for small to medium businesses and data or processing intensive home use.

The Plus Series

The Plus Series is the performance line of Synology NAS. They contain more memory and beefier processors in addition to features not enabled in the J or Value Series. Models range from those that support two drives to those that support 24 drives. All models in the series support the new B-Tree File System (Btrfs).

While some features and hardware specifically targeted to enterprise environments with dedicated data centers aren’t available, all the other features of DiskStation Manager are available and perform well.

The FS & XS Series

I view this series as the Data Center models. While models in the other series may be found in what’s considered an enterprise environment this line contains features that would be wasted in environments that don’t have a dedicated data center. The lowest cost model is about $2,500 before adding any drives.

Features that are unique to these models are not covered in this guide.


Hardware warranties range from two to five years. The models Synology targets to consumers and small businesses have a two year warranty. Models targeted to medium and large businesses, which are ones that support expansion units, have a three year warranty. Enterprise (FS and XS) models have a five year warranty. It comes as no surprise that the warranty length increases as the price increases. (These are rules of thumb for the warranties, always verify the warranty before buying your NAS.)

The Synology Replacement Service (SRS) is offered in some countries (not currently including the United States) and for selected models. This service is targeted to the enterprise and allows a replacement model (when covered under warranty) to be shipped before they receive the broken unit back. Currently supported countries and models can be found here.

Software Support

Synology will provide major firmware updates for about five years after a models release. Although after three years updates may be slower in coming and may eventually be limited to security updates and bug fixes. Synology may consider a “dot” release to be a major update. For example, when Synology moved from DSM 5.0 to DSM 5.1 they did not release new firmware for some older x10 models until a couple months after it’s initial release. Synology has one major DSM release per year so while DSM 5.0 to 5.1 may seem like a small “dot” upgrade, it was a year after the DSM 5.0 release and Synology considers it a major release.

These are not official Synology policies as Synology does not have an official policy or guarantee for firmware updates. They are based upon Synology’s recent practices. I would consider three years a conservative estimate for how long you should expect new features in your firmware updates and five years a reasonable estimate for security updates.

Synology lists the current support status of all their models here. While you’ll notice that “full” support extends well beyond my 3 year estimate I like to be conservative. Naturally, any new features would need to be supported by the hardware you have. While my DS1511+ is still getting full DSM updates after nearly 6 years it’s unable to support all the latest features such as Btrfs. I would expect new feature support to begin to diminish after 3 years, even if the latest DSM version can be installed.

Picking Your Synology Model

If you’re considering an enterprise model, the dedicated surveillance station or the embedded DiskStation then this section isn’t for you. If your looking for more general home or business use then read on.

When deciding on your Synology NAS think about the following:

  1. What is your budget?
  2. What will you use Synology for? (File storage, running applications/packages, backup of other computers.)
  3. How much disk space will you need?

The Short Answer

I really like the DS916+ (4 bay) and DS216+II (2 bay) models, or whatever the current model in the DS9xx+ and DS2xx+ series are. The DS415+ really towered above other models in bang for the buck and the DS916+ is it’s successor. It’s a DS9xx because it does support a expansion unit but it holds four drives out of the box. It’s become my most recommended NAS.

If you want to start small but have the option of expanding then the DS716+ is a good choice. It holds two drives out of the box but supports a 5-drive expansion unit. That said, I generally don’t recommend this model due to the cost, but there are places where it may be suitable.

For maximum expandability and flexibility, without getting into rack mounted or enterprise models, either the DS1517+ or DS1817+(or latest DS15xx+ or DS18xx+ series models) are excellent choices for people and businesses with a lot of data management needs. They have 5 (DS15xx+) or 8 (DS18xx+) drive bays and can add another 10 drives with the addition of two expansion units. This flexibility does come at a price (in dollars). I have used a DS1511+ for several years and it has served me well. It is still running daily as a backup destination. A DS1815+ has been my primary NAS for about two years and has also performed well, although it did require replacement under warranty.

One thing these recommendations all have in common is that they are all “+” (plus) models. The + (plus) models provide extra power to run applications so they’re ready for expansion as your needs grow.

If you’re just testing the Synology waters or have simple needs then I typically recommend the DS216J. It provides RAID protection while having enough power to run the basic apps.

The Long Answer

1. What’s Your Budget?

This is fairly straight-forward although you may want to reword this as “how much am I willing to spend?” Don’t then immediately go to the largest model you can afford, but if you have some extra money after reviewing the next two points you may want to consider stepping up to one with a better warranty and to allow for future expansion. Or you may simply decide to be a savvy shopper and save money.

2. What will you use the Synology for?

This is one of the potentially more complicated questions since a Synology NAS can do so much.

File Storage

The most common use of a NAS is to to store files. I have two active Synology NASs myself. One is used as my primary file storage, meaning the files I access and use on a regular basis. A second NAS is used as secondary storage, meaning archives and backups.

Will your Synology be used for primary storage, where everyone in your family or business can access the files? Will it be used for secondary storage – archiving and backup of your computer files with infrequent access? Or will it be used for both? Having two copies of your files on the same NAS is not a good choice as a backup solution (you’d lose both if the NAS drive failed), so by “both” I mean primary storage for some files and archive/backup for a separate set of files.

If you’ll be doing video or music streaming you should consider these files part of primary storage since you’ll want quick access.

Determining your disk space needs is covered in more detail in the Capacity Planning chapter.

The difference:

Primary storage: If you’ll be using the NAS for primary storage and will be accessing the files frequently you should skip the lower powered “J” models. An exception to the “J” exclusion is if only one person will be using the Synology, or at most one person at a time, and you’ve got a limited budget,

Secondary storage: If you’ll be using the NAS for secondary storage you’ll probably be less concerned about speedy real-time file access. A “J” model may be suitable for you.

Video Streaming

If you’ll be using your NAS for video streaming you’ll want a little more power or you’ll want a NAS customized for video streaming.

I generally recommend more power over video customization since the power can benefit all the ways you use your Synology. But if your primary use will be video streaming and maybe a little backup file storage then the “play” models are worth a look.

I would recommend avoiding the “J” models for video streaming unless your usage will be very light and you have a limited budget. If you have multiple family members who will be streaming different music or videos at the same time then the “J” models probably won’t meet your expectations.

Music Streaming

Streaming music is not a very intensive operation. It’s demand on the NAS is comparable to a constant file copy so this doesn’t affect your decision beyond the storage needs for your music and how many people will be accessing the music at one time.

Photo Storage (using Photo Station)

Photo Station is a great app for managing and viewing photos. Part of what it does is generate thumbnails. While it’s improved over time, this is still a processing intensive operation. If you’re a professional photographer or take a lot of photos I’d suggest one of the “+” models since they have more horsepower.

BitTorrent or other file downloading

Download Station can be used to download BitTorrent and other large files. If you’ll be doing this constantly, and use other applications at the same time you’ll want to avoid the “J” models. If your primary use will be for BitTorrent then you can use the “J” model since Download Station itself isn’t very intensive.

Other Applications

There’s so many applications available for Synology it’s impossible to list them all here. But if you expect to run multiple applications at the same time you’ll want a + (plus) model since these are designed to have the extra memory and horsepower needed to run multiple applications simultaneously.

Multiple Users

If you have multiple people who will be accessing the Synology NAS at the same time you’ll want to avoid a “J” model.

You may also want to consider a model that has two network ports and supports Link Aggregation/Network Load balancing. This means that the network traffic can take advantage of multiple network cards.

Note: DSM 5.2 added network load balancing which provides many of the benefits of link aggregation without requiring special network hardware. I find that this has worked well and doesn’t require any special network hardware.

3. How Much Disk Space Will You Need?

I cover this in more detail in the capacity planning chapter, For now I’ll just talk about the hard drive hardware and leave the quantity and sizes for the capacity planning chapter.

Picking The Right Hard Drives

Spinning Drive (HDD) or Solid State Drive (SSD)

Spinning Drives (HDDs) provide the most storage space for the buck. Solid State Drives (SSDs) provide much faster performance. The price of SSDs is also dropping. While they are still much more expensive per GB than a spinning drive, the cost is within reach for many people.

While there are exceptions, drive speed is not going to be the limiting factor in most home or small business setups so the added cost of an SSD will be wasted money. One of the exceptions is if the NAS is running several applications which are being accesses by many users at the same time and they expect fast responses. Unless you have special requirements and also design your network for performance you will not benefit from an SSD1. I’ve yet to encounter a home or small business where using only SSDs made sense. Generally, traditional hard drives have been able to provide the data fast enough.

Pick any hard drive brand and you’ll find it has it’s opponents and proponents. There’s also been a lot of consolidation in the hard drive industry. Western Digital and Seagate are the big players in the industry. Toshiba is a distant third. Hitachi, a popular brand, was bought by Western Digital but some of it’s business was sold to Toshiba to win regulatory approval. So what does all this mean to you? Nothing, except the brand doesn’t really matter so don’t worry about it2.

The primary factor in picking hard drive is verifying that it is on Synology’s compatibility list. Be sure to check the notes for any exclusions or limitations. I have used drives that weren’t on the list (especially in the early days of SSDs) but only when I was doing testing and didn’t want to buy drives. While I didn’t have any problems, your data (and time) are too valuable to risk on untested drives just to save a couple of bucks.

NAS’s are always on, so the drives are spinning a lot. (Unless you plan to power down the NAS when it’s not in use.) Because of this you’ll want to avoid drives promoted as desktop class, even if they’re on the compatibility list. Or, if you do use desktop class drives have a spare ready to swap in. If the drive fails in the warranty period you’ll be able to send it in for replacement.

A more recent development are drives promoted as “NAS drives”. These are typically less expensive than enterprise drives, but slightly more expensive than desktop class drives. Western Digital markets these as “Red” drives while Seagate used the unimaginative “NAS” moniker until recently when they introduced the “IronWolf” branding for their NAS drives. DSM has integrations which allow it to better monitor the health and performance of IronWolf drives which, in theory, makes them a good choice. NAS class drives are designed to be always on and are good choices for a Synology NAS.

There are various strategies promoted when buying drives for a NAS. One is to buy all the drives in a batch so they are likely to have the same firmware versions. Another is the exact opposite – buy them from two or more places so that if there are manufacturing problems with a specific batch you won’t have problems with multiple drives. Which is better? Flip a coin. Don’t worry about having the same firmware because DSM doesn’t even care if they are the same model drive.

I buy my drives in whatever way makes sense at the time. Synology is very forgiving of mixed drive types so feel free to mix and match. If you are starting out and have some spare drives available, use them to become familiar with DSM. If they are not on the compatibility list then be careful and always have backups.

I’ve never specifically bought drives from different places to mix the manufacturing batches. There may be some credibility to that theory, but I view it as increasing the chances of buying into a bad batch. Plus, I’m basically lazy and find it easier to place one order.

That said, these days I’m typically buying drives one or two at a time to upgrade an existing NAS, so they are naturally spread out, both by the manufacturing batch and the warranty expiration.

Some Additional Tips

I do like to keep the drive speeds (the rotation speed such as 5500 rpm or 7200 rpm) the same within the NAS, even if they are from different manufacturers or are different sizes. While Synology doesn’t care, as long as the drives are compatible, the slowest drive will dominate the performance of the volume. So having faster drives mixed in would be a waste.

While “green” may be nothing more than a marketing term in some cases, I try to avoid green drives even if they are on the compatibility list. They may be set to power down when not being actively accessed which could affect NAS performance. If a green drive is not on the compatibility list I would avoid it since it’s very likely that it’s not there for a specific reason.

You can determine how much usable space that you’ll have by using Synology’s RAID Calculator. I cover capacity planning in Chapter 3. But first we’ll define some terms and identify many of the features in DSM.

  1. Synology has recently added the ability to use SSD drives as a cache in the NAS in order to improve performance. In this case the drive is not part of the file storage and is a separate discussion. If you plan to use an SSD cache you need to allow extra drive bays for these drives. ↩︎
  2. I avoided Seagate when I had a bad run of drives from them. Then I avoided Western Digital after I had a bad run of those. Hitachi and Samsung both served me well but are now owned by Western Digital and Seagate. So I generally look at the current prices, performance and warranty when picking a drive. ↩︎