Introduction and Testbed Setup

Synology is one of the most popular COTS (commercial off-the-shelf) NAS vendors in the SMB / SOHO market segment. The NAS models introduced by them in 2014 were mostly based on Intel Rangeley (the Atom-based SoCs targeting the storage and communication market). However, in December, they sprang a surprise by launching the DS2015xs, an ARM-based model with dual 10GbE ports. We covered the launch of the Synology DS2015xs in December, and provided some details about the Annapurna Labs AL514 SoC in it.

ARM-based SoCs for SMB / SOHO NAS units typically support up to 4 bays and come with dual GbE links. Intel's offerings have had a virtual monopoly in the other tiers of the market. Synology's DS2015xs, with its native 10G capabilities, brings in another contender into the market.

The DS2015xs is 8-bay NAS unit presented as a step-up from the DS1815+. While the DS1815+ can expand up to a total of 18 bays with two DX513 expansion chassis, the DS2015xs is compatible with the 12-bay DX1215 expander (for a total of 20 bays). The main step-up from the DS1815+ is the presence of two built-in 10G SFP+ links (supporting direct-attach copper cables). The gallery below takes us around the unit's chassis.

The specifications of the Synology DS2015xs are provided in the table below

Synology DS2015xs Specifications
Processor Annapurna Labs AL514 SoC (Quad-Core Cortex-A15 @ 1.7 GHz)
Drive Bays 8x 3.5"/2.5" SATA II / III HDD / SSD (Hot-Swappable)
Network Links 2x 1 GbE RJ-45 + 2x 10GbE SFP+
External I/O Peripherals 2x USB 3.0, 1x Infiniband for Expansion Bay
Expansion Slots N/A
VGA / Display Out N/A
Full Specifications Link Synology DS2015xs Specifications
Price USD 1400

The Synology DS2015xs runs the latest DiskStation Manager OS, which, subjectively speaking, is one of the best COTS NAS operating systems in the market. Geared towards both novice and power users, it also provides SSH access. Some additional aspects can be gleaned through SSH. For example, the unit runs on Linux kernel version 3.2.40. The AL514 SoC has hardware acceleration for cryptography and two in-built USB 3.0 ports. There are also four network links (we know from external inspection that two are 10GbE, while the others are 1GbE) with unified drivers for both types of interfaces.

In the rest of the review, we will first take a look at the performance of the unit as a direct-attached storage device. This is followed by benchmark numbers for both single and multi-client scenarios across a number of different client platforms as well as access protocols. We have a separate section devoted to the performance of the NAS with encrypted shared folders. Prior to all that, we will take a look at our testbed setup and testing methodology.

Testbed Setup and Testing Methodology

The Synology DS2015xs can take up to 8 drives. Users can opt for different RAID types depnding on their requirements. We expect typical usage to be with multiple volumes in a RAID-5 or RAID-6 disk group. However, to keep things consistent across different NAS units, we benchmarked a SHR volume with single disk redundancy (RAID-5). Tower / desktop form factor NAS units are usually tested with Western Digital RE drives (WD4000FYYZ). However, the presence of 10-GbE on the DS2015xs meant that SSDs had to be used to bring out the maximum possible performance. Therefore, evaluation of the unit was done by setting up a RAID-5 volume with eight OCZ Vector 4 120 GB SSDs. Our testbed configuration is outlined below.

AnandTech NAS Testbed Configuration
Motherboard Asus Z9PE-D8 WS Dual LGA2011 SSI-EEB
CPU 2 x Intel Xeon E5-2630L
Coolers 2 x Dynatron R17
Memory G.Skill RipjawsZ F3-12800CL10Q2-64GBZL (8x8GB) CAS 10-10-10-30
OS Drive OCZ Technology Vertex 4 128GB
Secondary Drive OCZ Technology Vertex 4 128GB
Tertiary Drive OCZ Z-Drive R4 CM88 (1.6TB PCIe SSD)
Other Drives 12 x OCZ Technology Vertex 4 64GB (Offline in the Host OS)
Network Cards 6 x Intel ESA I-340 Quad-GbE Port Network Adapter
Chassis SilverStoneTek Raven RV03
PSU SilverStoneTek Strider Plus Gold Evolution 850W
OS Windows Server 2008 R2
Network Switch Netgear ProSafe GSM7352S-200

The above testbed runs 25 Windows 7 VMs simultaneously, each with a dedicated 1 Gbps network interface. This simulates a real-life workload of up to 25 clients for the NAS being evaluated. All the VMs connect to the network switch to which the NAS is also connected (with link aggregation, as applicable). The VMs generate the NAS traffic for performance evaluation.

Thank You!

We thank the following companies for helping us out with our NAS testbed:

DAS Evaluation Setup and Methodology

In addition to our standard NAS evaluation suite, the Synology DS2015xs also warrants investigation under ideal network conditions as a direct-attached storage unit. The presence of 10G network links in the unit has prompted Synology to market it as a fast DAS unit for video production workflows. In order to evaluate this aspect, we augmented our DAS testbed with an Emulex OneConnect OCe11102(R)-N 2-port 10GbE SFP+ PCIe NIC and a OCZ Vector 120 GB SSD.

The Emulex PCIe NIC doesn't support teaming under Windows 8.1. Therefore, we had to install Windows Server 2012 R2 on the additional SSD to make our DAS testbed dual-boot for evaluating NAS units. The DHCP Server feature was also activated on the teamed port to which the NAS's 10G ports were connected. On the NAS side, the ports were set up for teaming too and configured to receive an IP address from a DHCP server. The MTU for the interface was configured to be 9000 bytes. The details of the tests that were run in this mode will be presented along with the performance numbers in the next section.

Direct-Attached Storage Performance
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  • DCide - Friday, February 27, 2015 - link

    Ganesh, thanks for the response. Unless you really know the iperf code (I sure don't!) I don't believe you can make many conclusions based on the iperf performance, considering you hit a CPU bottleneck. There's no telling how much of that CPU went to other operations (such as test data creation/reading) rather than getting data across the pipe. Because of the bottleneck, the iperf results could easily have no relationship whatsoever to SSD RAID R/W performance across the network, which might not be bottlenecking at all (other than the 10GbE limits themselves, which is what we want).

    Could you please run a test with a couple of concurrent robocopys (assuming you can run multiple instances of robocopy)? I'm not sure the number of threads necessarily effects whether both teamed network interfaces are utilized. Please correct me if I'm wrong, but I think it's worth a try. In fact, if concurrent robocopys don't work, it might be worth trying concurrently running any other machine you have available with a 10GbE interface, to see if this ~1GB/s barrier can be broken.
  • usernametaken76 - Friday, February 27, 2015 - link

    Unless we're purchasing agents for the government, can we avoid terms like "COTS"? It has an odor of bureaucracy associated with it.
  • FriendlyUser - Saturday, February 28, 2015 - link

    I am curious to find out how it compares with the AMD-based QNAP 10G NAS ( I suppose the AMD cores, at 2.4GHz, are much more powerful.
  • Haravikk - Saturday, February 28, 2015 - link

    I really don't know what to make of Synology; the hardware is usually pretty good, but the DSM OS just keeps me puzzled. On the one hand it seems flexible which is great, but the version of Linux is a mess, as most tools are implemented via a version of BusyBox that they seem unwilling to update, even though the version has multiple bugs with many of the tools.

    Granted you can install others, for example a full set of GNU tools, but there really shouldn't be any need to do this if they just kept it up-to-date. A lack of ZFS or even access to BTRFS is disappointing too, as it simply isn't possible to set these up yourself unless you're willing to waste a disk (since you HAVE to setup at least one volume before you could install these yourself).

    I dunno; if all I'm looking for is storage then I'm still inclined to go Drobo for an off-the-shelf solution, otherwise I'd look at a ReadyNAS system instead if I wanted more flexibility.
  • thewishy - Wednesday, March 4, 2015 - link

    I think the point you're missing is that people buying this sort of kit are doing so because they want to "Opt out" of managing this stuff themselves.
    I'm an IT professional, but this isn't my area. I want it to work out the box without much fiddling. The implementation under the hood may be ugly, but I'm not looking under the hood. For me it stores my files with a decent level of data security (No substitute for backup) and allows me to add extra / larger drivers as I need more space, and provides a decent range of supported protocols (SMB, iSCSI, HTTP, etc)
    ZFS and BRTFS are all well and good, but I'm not sure what practical advantage it would bring me.
  • edward1987 - Monday, February 22, 2016 - link

    You can get 1815+ a bit cheaper if you don't really need enterprise class:
  • Asreenu - Thursday, September 14, 2017 - link

    We bought a couple of these a year ago. All of them had component failures and support is notorious for running you through hoops until you give up because you don't want to be without access to your data for so long. They have ridiculous requiresments to prove your purchase before they even reply to your question. In all three cases we ended up buying replacements and figuring out how to restore data ourselves. I would stick with netgear for the support alone because that's a major sell. Anandtech shouldn't give random ratings to things they don't have experience with. Just announcing they have support doesn't mean a thing.

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