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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  • M4stakilla - Monday, March 2, 2015 - link

    I currently have a 1TB M550 and 6x 4TB desktop HDDs (will expand to 8x) in RAID5 + an offline backup (5x 4TB)

    So nothing exceeds 500MB/sec and no real upgrade plans for that either

    but it would be a a shame to waste 400MB/sec of the 500MB/sec on stupid network limitations

    4x 1Gbit teamed might be worth a look though, thanks
  • usernametaken76 - Friday, February 27, 2015 - link

    Yes, a Mac Mini with Thunderbolt and, just one example, a LaCie 5big Thunderbolt (in sizes from 10 to 30 TB) does offer exactly this, almost times 2. The Thunderbolt 2 models, even more. These are geared more towards video editing but provides every bit of the bandwidth you crave.
  • M4stakilla - Sunday, March 1, 2015 - link

    Thanks for the advice!

    Looking further into Thunderbolt... Cabling seems quite expensive though : 300+ euro for 10m, 500+ euro for 20m :(

    Out of ethical reasons, I'm trying to avoid Apple at all costs, so no Mac Mini for me...
    Also the LaCie 5big is a bit silly, as I already have the HDDs and the LaCie is including HDDs.
  • usernametaken76 - Tuesday, March 3, 2015 - link

    You can get four drive empty Thunderbolt cases from OWC. And of course a PC motherboard with Thunderbolt are available via add-in card, Asus makes a good Z97 board for about $400 with everything but the kitchen sink. Not sure why you're seeing such high prices for a 10m cable. They shouldn't be more than $50 for a 6m cable. They were working on optical cable extensions to the original copper cabling (with Mini-DP headers)..perhaps that's what you're seeing?
  • usernametaken76 - Tuesday, March 3, 2015 - link

    Make that $39 for a 2m cable. I believe you are looking at active optical cables that you wouldn't need unless you have to have a very long run for some reason. Is there a reason the storage has to be so far away from the workstation?
  • DCide - Friday, February 27, 2015 - link

    I'm unclear about the DAS tests. It appears you were testing throughput to a single Windows Server 2012 client. I would expect the ATTO read throughput to top out at around 1200MBps, and the real-world read performance to top out around 900-950MBps, as it did.

    I thought teaming didn't usually increase throughput to a single client from the same source. I imagine Synology's claim of around 1900MBps throughput will pan out if two clients are involved, perfectly inline with your real-world throughput of 950MBps to a single client.
  • usernametaken76 - Friday, February 27, 2015 - link

    A single client with multiple transfers would be treated as such.
  • usernametaken76 - Friday, February 27, 2015 - link

    That is, provided the single client also has teaming configured.
  • DCide - Friday, February 27, 2015 - link

    I think teaming was configured - that was the point of using Windows Server 2012 for the client, if I understood correctly.

    So it would appear that both tests (ATTO & real world) only consisted of a single transfer. I don't see any evidence that two Blu-ray folders were transferred concurrently, for example.
  • ganeshts - Friday, February 27, 2015 - link

    Our robocopy tests (real world) were run with MT:32 option. The two Emulex SFP+ ports on Windows Server 2012 were also teamed. In one of the screenshots, you can actually see them even treated separately (no teaming) and iPerf reporting around 2.8 Gbps each. In the teamed case, iPerf was reporting around 5 Gbps. iPerf was run with 16 simultaneous transfers.

    I will continue to do more experiments with other NAS units to put things in perspective in future reviews. As of now, this is a single data point for the Synology DS2015xs.

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