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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  • Essence_of_War - Friday, February 27, 2015 - link


    I understand why you used 120 GB SSDs for performance to try to capture the maximum throughput of the 10GbE, but I was confused to see that you stuck with those for things like raid expansion/rebuild etc.

    Was it a time constraint, or is this a change to the review platform in general? Is 8x small capacity SSDs in a RAID-5 an effective benchmark of RAID-5 rebuild times?
  • DanNeely - Friday, February 27, 2015 - link

    When Ganesh reviewed the DS1815 using HDDs for the rebuild it took almost 200 hours to do all the rebuild tests. (Probably longer due to delays between when one finished and the next was started.) That sort of test is prohibitively time consuming.
  • Essence_of_War - Friday, February 27, 2015 - link

    Yikes, when put that in context, that makes a lot more sense. I think we can reasonably extrapolate for larger capacities from the best-case scenario SSDs.
  • DanNeely - Friday, February 27, 2015 - link

    Repeating a request from a few months back: Can you put together something on how long/well COTS nas vendors provide software/OS updates for their products?
  • DigitalFreak - Friday, February 27, 2015 - link

    Synology is still releasing new OS updates for the 1812+ which is 3 years old.
  • DanNeely - Saturday, February 28, 2015 - link

    I poked around on their site since only 3 years surprised me; it looks like they're pushing full OS updates (at least by major version number, I can't tell about feature/app limits) as far back as the 2010 model with occasional security updates landing a few years farther back.

    That's long enough to make it to the upslope on the HDD failure bathtub curve, although I'd appreciate a bit longer because with consumer turnkey devices, I know a lot of the market won't be interested in a replacement before the old one dies.
  • M4stakilla - Friday, February 27, 2015 - link

    Currently I have a desktop with an LSI MegaRAID and 8 desktop HDDs.
    This is nice and comfortably fast (500MB/sec+) for storing all my media.

    Soon I will move from my appartement to a house and I will need to "split up" this desktop into a media center, a desktop pc and preferably some external storage system (my desktop uses quite some power being on 24/7).

    I'd like this data to remain available at a similar speed.

    I've been looking into a NAS, but either that is too expensive (like the above 1400$ NAS) or it is horribly slow (1gbit).

    Does anyone know any alternatives that can handle at least 500MB/sec and (less important, but still...) a reasonable access time?
    A small i3 / celeron desktop connected with something other than ethernet to the desktop? USB3.1 (max cable length?) Some version of eSATA? Something else? Would be nice if I could re-use my LSI megaRAID.

    Anyone have ideas?
  • SirGCal - Friday, February 27, 2015 - link

    Honestly, for playing media, you don't need speed. I have two 8 drive rigs myself, one with an LSI card and RAID 6 and one using ZFS RAIDZ2. Even hooked up to just a 1G network, it's still plenty fast to feed multiple computers live streaming BluRay content. Use 10G networks if you have the money or just chain multiple 1G's together within the system to enhance performance if you really need to. I haven't needed to yet and I host the entire house right now of multiple units. I can hit about 7 full tilt before the network would become an issue.

    If you're doing something else more direct that needs performance, you might consider something else then a standard network connection. But most people, using a 4-port with teaming 1G network PCIe card would be beyond overkill for the server.
  • M4stakilla - Sunday, March 1, 2015 - link

    I do not need this speed for playing media ofcourse ;)
    I need it for working with my media...

    And yes, I do need it for that... it is definately not a luxuary...
  • SirGCal - Sunday, March 1, 2015 - link

    Ahh, I work my media on my regular gaming rig and then just move the files over to the server when I'm finished with them. However, without using something specific like thunderbolt, your cheapest options (though not really CHEAP) might still be using two of the 4-port teamed 1G connections. That should give you ~ 400M throughput since I get about 110M with a single 1G line. Teaming loses a tiny bit but. You'd need it at both ends. Or get a small 10G network going. I got a switch from a company sale for < $200, cards are still expensive though, realistically your most expensive option. But a single connection gets you ~ 1100M throughput.

    I plan on getting the new Samsung SM951. Given 2G reads, something like 1.5G writes, that might be your cheapest option. Even if you need to get a capable M.2 PCIe riser card to use it. Then you just have transfer delays to/from the server. Unless 512G isn't enough cache space for work (good lord). Again, something like that might be your cheapest option if plausible.

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