Synology DiskStation DS1817

Those who have tracked Synology NAS hardware over the past 13 years since its first NAS box was released may have noticed a subtle evolution. Namely, a shift from single-core ARM-based hardware to progressively more powerful architectures, given the increasing demands that home and business users are making on their gear.

At the heart of this movement is Synology’s DSM operating system, a Linux derivative built to provide a solid platform for both file serving and services. It now sports nearly 100 installable applications, and the temptation is there to use more of them simultaneously.

That’s the scenario that the DS1817 is built to address, handling multiple service functions and lots of users, while providing a failure-resistant storage facility.

Pricing and availability

The DS1817 costs £827 ($850 in the US) without any drives, almost the same price as its next-tier DS1817+ (2GB) brother. While the pricing is somewhat confusing, it’s cheaper than the comparable QNAP TVS-863+ 4GB at £1,198, and much less than Netgear’s ReadyNAS 528X at £1,144 ($1,600).

The obvious choice might be to get even more processing power and M.2 module support in the DS1817+. That would work, although the DS1817+ doesn’t come with 10GbE out of the box, requiring the extra expense of adding a 10GbE PCIe card.

The initial cost of these devices can be a moot point in many respects, however, simply because filling them up with 10TB drives is likely to cost you three times as much as the machine – and that’s not the end of the outlay.

With eight slots to fill you do have the option to partially occupy the bays, then add more drives later. But our experience is that this isn’t the wisest course to take, as this mixing of drive specs and sizes can often become problematic, as can volume resizing exercises.

A better use of those slots is to leverage the possible capacity or create multi-layered redundancy. The options are numerous: mirroring, redundant array and the allocation of hot-swap drives ready to jump into action if the array goes critical due to failure.

All these possibilities are available for those who have a healthy level of data loss paranoia, in whatever way they wish to express it.

This hardware isn’t cheap, but on balance it’s acceptably priced considering the high build quality, scalability and flexibility that the DS1817 has to offer.

As for availability, the DS1817 should go on sale globally later this month.

Design and features

From the outside the DS1817 is practically identical to the design of the DS1815, which is the unit that this offering supersedes. However, there is something inherently calming about Synology’s signature black drive enclosure with an embossed logo on the side.

There are some minor differences, but other than the tiny DS1817 label you’d be hard-pressed to tell them apart at first glance.

They both accept up to eight 3.5-inch or 2.5-inch SATA drives, giving a potential array of 80TB with current drive options. With optional external expansion boxes (DX517) you can add a further 10 drives and boost total capacity to a gargantuan 180TB.

The only real limitation of this scale is the maximum single volume capacity of 108TB, should you have an enormous amount of data you’d like to access in a single file structure. 

To get all those drives to spin in unison, Synology utilised the Annapurna Labs Alpine AL-314 CPU – a quad-core Cortex-A15 SoC clocked at 1.7GHz.

The system comes with 4GB of DDR3L memory in a single socket, and an easily accessible second socket enables that to be increased to 8GB.

Network connectivity is excellent, having both dual 1GbE LAN ports and dual 10GbE ports. Each of these dual port combinations can be organised either to link aggregate or failover depending on your priorities.

There are also two eSATA ports for connecting the external drive enclosures, and a pair of USB 3.0 Type-A ports for connecting portable storage or a USB peripheral (printer) that you may wish to network share.

Our only query about the specification of this design is that surely more than two USB ports could have been squeezed out of this SoC.

A quick word on the use of eSATA as an expansion technology – this seems dated, as all the drives connected through it effectively share the bandwidth of a single SATA III port.

With conventional hard drives this is not a significant limitation, though it would be if you used SSDs or Hybrid drives in the expansion box.

The motivation for Synology to use a technology with more bandwidth, like Thunderbolt 2, is that the firm might be able to offer eight bay expansions, and not just five.

Being a ‘Value Series’ design, the DS1817 targets the advanced home user or small workgroup deployment.

Traditionally these machines aren’t powerful or upgradable and they don’t contain high-end features. The DS1817 seems to fly in the face of all those criteria, being the first Value Series DiskStation that Synology has made with user accessible RAM sockets and 10GbE networking.


Gauging the performance of hardware like the DS1817 is challenging in the extreme, given all the variables at play (drives, drive numbers, array structure, network connections, aggregation and client).

But what can be said with some certainty is that almost irrespective of what drives are inside the DS1817, it can fully flood bonded dual gigabit channels.

Under Windows a single 1GbE connected client experiences about 110MB/s reading and writing, the total sum of what gigabit Ethernet has to offer.

A single client with dual gigabit ports channel bonded at both ends boosts that to 200MB/s performance, logically.

While that works perfectly, it is the digital equivalent of trying to push an elephant through a keyhole – simply because the internal bandwidth of the DS1817 is so much greater, and that can only be fully exposed once connected via 10GbE technology.

According to Synology’s tests, the DS1817 can achieve 1,577.61MB/s reads and 739.75MB/s writes, making it quicker than even the DS1817+ at sequential throughput.

For those wondering, the Intel Atom C2538 in the DS1817+ only starts to show its true worth in iSCSI Random IOPS. The DS1817+ (8GB) can execute nearly 25K random IOPS (4K) writes, where the DS1817 only achieves about 50% of that. Read speeds are only 4% less on the DS1817, however.

The message here is that the DS1817 is better suited to supporting a small, if demanding, workgroup, where the DS1817+ has greater scope to handle a more varied workload.

While it is possible for a single 10GbE connected client to see greater than 350MB/s performance, the DS1817 was primarily designed to share network bandwidth rather than focusing it exclusively on a single computer.

In the file serving function, the DS1817 can easily handle 16 or more very active users when using a 10GbE downlink to a switch that connects 1GbE clients.

However, there are some important caveats here. The cheapest 10GbE switch with 802.3ad link aggregation easily costs almost as much as the DS1817.

Once you’ve accepted that additional expense, you might also run into some other issues getting the highest level of performance out of the DS1817.

The theoretical maximum speed of a single 10GbE port is 1,250Mb/s, but realistically around 60% of that level is possible. Both 10GbE ports must be working perfectly to hit the DS1817’s read performance limit if the connected clients can handle that throughput.

And, having all eight drives rolling with no redundancy would put a demand of maintaining nearly 200MB/s from each mechanism, a speed level that challenges conventional NAS drive hardware.

To make this more achievable you could blow the budget entirely by installing SSDs. Thankfully you don’t need to go that far, as the DSM operating system can connect them as ‘SSD Cache’, to enhance the performance of your conventional spinning rust.

Given all the boxes that need ticking here, where 10GbE makes better sense on this design is as a back-channel for connecting two of these machines and keeping the contents synchronised as an additional level of failover and redundancy.

Or, using a single 10GbE port direct to a single suitably enabled PC, and the other to distribute to a wider network.

An Intel X540 Chip PCIe card with a single 10GbE port on it costs around £180 ($180 in the US) and that will enable a directly connected PC to talk to the DS1817 at more than 400MB/s without a switch, using only a CAT6 cable.

The performance of the DS1817 is good on gigabit Ethernet using just WD Red drives for most users, but it can be elevated to much higher levels if you’re prepared to splash out on 10GbE technology and trade some of that massive capacity for SSD caching.

The Synology experience

As impressive as the DS1817 hardware is, the deal maker for many customers is its extensible OS: DSM 6.1.

This operating system is consistent across Synology’s entire NAS range, with the only differences being the precise selection of apps that each device supports based on its hardware specification.

Being a notch above entry-level, the DS1817 can handle a very wide selection of apps, and it also supports the commonly used virtualisation environments like VMware, Citrix, and Microsoft Hyper-V certificates.

There’s a reasonable argument that the DSM applications aren’t the full experience that you might see from a properly configured Linux server platform. But the flipside of that is that in this form they’re more easily administered and require much less expertise to operate.

Creating a mail server, Radius server, VP Server, Apache Web Server, Drupal platform or dozens of other functions are just a few clicks away.

Other brands have attempted to ape DSM in their platforms, but Synology’s OS stands out as having the best third-party application support and excellent core functionality.

We liked

This NAS is easy to configure, deploy and use. The DS1817 embodies everything that’s right about the Synology ethos, which addresses business customer needs in flexible server technologies.

The inclusion of 10GbE ports with failover allows the huge bandwidth available in an eight drive array to be shared amongst a decent number of gigabit switch connected users, without creating a significant bandwidth bottleneck.

But above all else, the DS817 offers a very wide level of scalability that could start with 1GbE networking and a handful of drives, and extend to linked 10GbE and potentially 180TB of accessible storage.

The choice to use the 10GbE option directly from a single computer without a switch is also an attractive proposition. It’s perfect for those who want to use the DS1817 as an alternative to Thunderbolt external storage, with the added bonus of wider network access.

We disliked

Synology needs to stop using eSATA to connect expansion boxes, as it bottlenecks the performance of drives on that side of the array. Using USB 3.1 or Thunderbolt 2 would be the obvious alternatives to increase available bandwidth to external storage.

A possible weakness of the Alpine AL-314 32-bit CPU is that it can’t match the iSCSI IOPS of the 64-bit Intel Atom C2538 in the DS1817+, even if it is quicker at most other things.

The pricing of this NAS, with a tag which almost matches the DS1817+, might confuse many customers unless they’re committed to 10GbE networking from the outset.

Final verdict

Synology has successfully occupied the high ground for affordable NAS solutions, and the DS1817 just reinforces that position. It’s ideal for a small business that wants an easy to deploy and maintain solution that can be rapidly expanded should data storage requirements blossom. And with 10GbE pre-installed, it provides the first rung on the ladder to the next level of network performance, when the customer is ready to take that step.

Its inclusion should put pressure on switch makers to deliver more affordable 10GbE solutions, as the market is ready to embrace the tech.

Being ARM-based, this is never going to compete with the Xeon-based servers, but for those who want reliable file serving with lots of capacity, or to meet a specific need, there is plenty here to recommend.

By Mark Pickavance

from Blogger


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