Original Link: https://www.anandtech.com/show/8659/synology-ds415-review-dsm-on-intel-rangeley
Synology DS415+ Review: DSM on Intel Rangeley
by Ganesh T S on October 30, 2014 7:30 AM EST- Posted in
- Storage
- Intel
- NAS
- Synology
- Silvermont
- Enterprise
- Rangeley
Introduction and Testbed Setup
Synology launched the DS415+ last month. It is their first product based on the Intel Rangeley platform. One must note that Synology is not the first COTS NAS vendor to bring out a product based on the new Atom SoCs. That credit goes to Seagate for their NAS Pro lineup. However, unlike the dual core Rangeley variant used by Seagate, Synology has opted for a quad-core version that is clocked higher. This makes sense, since Synology's Disk Station Manager OS (DSM) is quite advanced compared to Seagate's NAS OS (which is in the early stages of its life cycle). There are plenty of third-party apps for DSM users. The more the horsepower at the disposal of the end user, the better it is in scenarios where they have multiple apps running.
The DS415+ is a typical 4-bay SMB NAS with dual GbE ports and a host of virtualization certifications. The major attraction is the availability of AES-NI in the Rangeley series of Atom SoCs. Enabling encryption of shared folders should result in minimal performance impact. Other than that, the Rangeley SoCs bring in an updated Atom microarchitecture along with lower power consumption. These aspects should help the DS415+ make a compelling case over the other 4-bay units from Synology based on the older Atoms. The specifications of the DS415+ are provided in the table below.
Synology DS415+ Specifications | |
Processor | Intel Atom C2538 (4C/4T Silvermont x86 Cores @ 2.40 GHz) |
RAM | 2 GB DDR3 RAM |
Drive Bays | 4x 3.5"/2.5" SATA 3 Gbps HDD / SSD (Hot-Swappable) |
Network Links | 2x 1 GbE |
External I/O Peripherals | 2x USB 3.0, 1x USB 2.0, 1x eSATA |
Expansion Slots | None |
VGA / Display Out | None |
Full Specifications Link | Synology DS415+ Specifications |
Price | $600 (Amazon) |
The gallery below takes us around the DS415+. The chassis is retained from the previous-generation 4-bay NAS units (such as the DS412+ and DS413).
In addition to the standard drive mount screws, quick start guide and US power plug, the main unit was also accompanied by a 100 W power adapter (12V @ 8.33A).
In the rest of the review, we will first look at the Intel Rangeley platform in detail and how the Synology DS415+ takes advantage of it. 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 DS415+ 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 DS415+ can take up to four drives. Users can opt for either JBOD, RAID 0, RAID 1, RAID 5, RAID 6 or RAID 10 configurations. We benchmarked the unit in RAID 5 with four Western Digital WD4000FYYZ RE drives as the test disks. 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:
- Thanks to Intel for the Xeon E5-2630L CPUs and the ESA I-340 quad port network adapters
- Thanks to Asus for the Z9PE-D8 WS dual LGA 2011 workstation motherboard
- Thanks to Dynatron for the R17 coolers
- Thanks to G.Skill for the RipjawsZ 64GB DDR3 DRAM kit
- Thanks to OCZ Technology for the two 128GB Vertex 4 SSDs, twelve 64GB Vertex 4 SSDs and the OCZ Z-Drive R4 CM88
- Thanks to SilverStone for the Raven RV03 chassis and the 850W Strider Gold Evolution PSU
- Thanks to Netgear for the ProSafe GSM7352S-200 L3 48-port Gigabit Switch with 10 GbE capabilities.
- Thanks to Western Digital for the four WD RE hard drives (WD4000FYYZ) to use in the NAS under test.
Platform Analysis
The higher end segment of the SOHO / SMB NAS market uses Intel's Core-series and Xeon CPUs to deliver the required performance while supporting a large number of drive bays (typically more than 8, in a rackmount form-factor). Over the last four years or so, Intel's play in the other tiers has been mainly with its Atom CPU lineup. Back in 2010, Intel pushed the 45 nm Atom D410 / D510 / D525 for NAS units. In 2012, it was the 32 nm Atoms, the D2550 and D2700. All of these were based on the in-order Bonnell microarchitecture which was fast becoming dated compared to the advancements being made by the ARM SoC vendors. In moving from 32nm to 22nm, Intel completely revamped the microarchitecture for their Atom cores. Bonnell was replaced by Silvermont, bringing out of order execution and other improvements into the picture. Silvermont's applicability to a variety of power profiles meant that there were multiple product lines that ended up using the CPU cores. Bay Trail is proving very effective in tablets and also makes up QNAP's TS-x51 and TS-x53 Pro NAS series. Merrifield and Moorefield are trying to break into smartphones, but it is Avoton and Rangeley that are more relevant to the storage appliances market.
The different product lines integrated different I/O around the Silvermont cores depending on the target market. Avoton is meant for microservers and cloud storage platforms, while Rangeley is meant for communication and network infrastructure. Both of them integrate similar I/O around the cores, but the Rangeley parts have an updated crypto engine. The block diagram of a generic Rangeley part is provided below.
There is a wealth of I/O (2x SATA Gen 3, 4x SATA Gen 2 and up to 16 PCIe 2.0 lanes) for the storage subsystem, and the parts also support up to 4x 2.5 Gbps network links. From the viewpoint of the Synology DS415+, the above block diagram should be considered in the context of the information gleaned via SSH access to the unit.
The DS415+ uses the Intel Atom C2538 SoC which has four Silvermont cores running at 2.4 GHz. It is backed up by 2 GB of DRAM. The Atom C2538 has 16 PCIe 2.0 lanes across four controllers. The Silicon Image SiI3132 PCIe to 2-port SATA II host controller uses a single PCIe 2.0 lane on the host side. The device side can support port multipliers. Synology indicates that the eSATA port on the DS415+ can be used to connection an expansion chassis. However, unlike the scalable series, the external chassis can't be used to expand existing volumes in the main unit. The other chip connected to the SoC via PCIe is the Etron EJ168 USB 3.0 host controller. It also uses a single PCIe 2.0 lane on the host side and provides two USB 3.0 ports. These two enable the eSATA and the 2x USB 3.0 ports on the rear of the unit. The single USB 2.0 port in the front comes directly off the Atom C2538. Obviously, in a platform like Intel Rangeley, there is no need for SATA - PCIe bridges.
The more interesting aspect is the two Ethernet controllers. Unlike the Intel I211 GbE controllers in the Seagate NAS Pro 4-bay that we looked at earlier, the Synology DS415+ uses the Intel I354 2.5G Ethernet controllers. Despite being 2.5G-capable, Synology only advertises GbE links [Update: Synology clarified that even though the controllers are rated for 2.5Gbps, the transceivers they are linked to limit the rate to 1 Gbps]. Perhpaps, when the NBASE-T Alliance initiatives take off, we can get official 2.5Gbps ecosystem support from Synology as well as affordable and efficient peripherals. Current 10GBASE-T switches still need some updates to be more power efficient, and adoption is still not high enough to force pricing downwards.
On the software front, the DS415+ runs Linux (kernel version 3.2.4). We have covered DSM 5.0's setup and usage impressions in our recent DS214play and DS414j reviews. There is not much point in rehashing the same excellent setup and usage experience. That said, with the ioSafe 1513+, we also started looking at iSCSI support in NAS units. We will be looking at that aspect in this review also.
Single Client Performance - CIFS & iSCSI on Windows
The single client CIFS and iSCSI performance of the Synology DS415+ was evaluated on the Windows platforms using Intel NASPT and our standard robocopy benchmark. This was run from one of the virtual machines in our NAS testbed. All data for the robocopy benchmark on the client side was put in a RAM disk (created using OSFMount) to ensure that the client's storage system shortcomings wouldn't affect the benchmark results. It must be noted that all the shares / iSCSI LUNs are created in a RAID-5 volume. The DS415+ manages to compare favorably against the ARM-based solutions, obviously. The real tussle in these single client scenarios is not against the other Rangeley NAS (Seagate NAS Pro), but against the QNAP TS-451 based on Bay Trail-D. Both DSM and QTS are mature operating systems. The higher core count in the DS415+'s Atom C2358 compared to the TS-451's Celeron J1800 probably help the former edge ahead in most of the benchmarks presented in the graphs below.
We created a 250 GB iSCSI LUN / target and mapped it on to a Windows VM in our testbed. The same NASPT benchmarks were run and the results are presented below. The observations we had in the CIFS subsection above hold true here too.
Single Client Performance - CIFS and NFS on Linux
A CentOS 6.2 virtual machine was used to evaluate NFS and CIFS performance of the NAS when accessed from a Linux client. We chose IOZone as the benchmark for this case. In order to standardize the testing across multiple NAS units, we mount the CIFS and NFS shares during startup with the following /etc/fstab entries.
//<NAS_IP>/PATH_TO_SMB_SHARE /PATH_TO_LOCAL_MOUNT_FOLDER cifs rw,username=guest,password= 0 0
<NAS_IP>:/PATH_TO_NFS_SHARE /PATH_TO_LOCAL_MOUNT_FOLDER nfs rw,relatime,vers=3,rsize=32768,wsize=32768,namlen=255,hard,proto=tcp,timeo=600,retrans=2, sec=sys,mountaddr <NAS_IP>,mountvers=3,mountproto=udp,local_lock=none,addr=<NAS_IP> 0 0
The following IOZone command was used to benchmark the CIFS share:
IOZone -aczR -g 2097152 -U /PATH_TO_LOCAL_CIFS_MOUNT -f /PATH_TO_LOCAL_CIFS_MOUNT/testfile -b <NAS_NAME>_CIFS_EXCEL_BIN.xls > <NAS_NAME>_CIFS_CSV.csv
IOZone provides benchmark numbers for a multitude of access scenarios with varying file sizes and record lengths. Some of these are very susceptible to caching effects on the client side. This is evident in some of the graphs in the gallery below.
Readers interested in the hard numbers can refer to the CSV program output here.
The NFS share was also benchmarked in a similar manner with the following command:
IOZone -aczR -g 2097152 -U /nfs_test_mount/ -f /nfs_test_mount/testfile -b <NAS_NAME>_NFS_EXCEL_BIN.xls > <NAS_NAME>_NFS_CSV.csv
The IOZone CSV output can be found here for those interested in the exact numbers.
A summary of the bandwidth numbers for various tests averaged across all file and record sizes is provided in the table below. As noted previously, some of these numbers are skewed by caching effects. A reference to the actual CSV outputs linked above make the entries affected by this effect obvious.
Synology DS415+ - Linux Client Performance (MBps) | ||
IOZone Test | CIFS | NFS |
Init Write | 85 | 81 |
Re-Write | 83 | 80 |
Read | 49 | 136* |
Re-Read | 50 | 137* |
Random Read | 28 | 65 |
Random Write | 78 | 76 |
Backward Read | 28 | 54 |
Record Re-Write | 50 | 1695* |
Stride Read | 45 | 115 |
File Write | 83 | 80 |
File Re-Write | 83 | 80 |
File Read | 34 | 95 |
File Re-Read | 36 | 95 |
*: Benchmark number skewed due to caching effect |
Multi-Client Performance - CIFS on Windows
We put the Synology DS415+ through some IOMeter tests with a CIFS share being accessed from up to 25 VMs simultaneously. The following four graphs show the total available bandwidth and the average response time while being subject to different types of workloads through IOMeter. The tool also reports various other metrics of interest such as maximum response time, read and write IOPS, separate read and write bandwidth figures etc. Some of the interesting aspects from our IOMeter benchmarking run can be found here.
The attractiveness of the Rangeley platform is brought out by the latencies observed when subject to heavy loading. This is one of the key metrics that shows the advantage of a a SoC tuned towards storage appliances (particularly when compared to the previous-generation Atom platforms).
Multi-Client iSCSI Evaluation
As virtualization becomes more and more popular even in home / power user settings, the importance of the iSCSI feature set of any COTS NAS can't be overstated. Starting with our ioSafe 1513+ review, we have started devoting a separate section (in the reviews of NAS units targeting SMBs and SMEs) to the evaluation of iSCSI performance. Since we have already looked at the way iSCSI LUNs are implemented in DSM in the ioSafe 1513+ review, it won't be discussed in detail.
We evaluated the performance of the DS415+ with file-based LUNs as well as configuring a RAID-5 disk group with a single LUN. The standard IOMeter benchmarks that we used for multi-client CIFS evaluation were utilized for iSCSI evaluation also. The main difference to note is that the CIFS evaluation was performed on a mounted network share, while the iSCSI evaluation was done on a 'clean physical disk' (from the viewpoint of the virtual machine).
Performance Numbers
The four IOMeter traces were run on the physical disk manifested by mapping the iSCSI target on each VM. The benchmarking started with one VM accessing the NAS. The number of VMs simultaneously playing out the trace was incremented one by one till we had all 25 VMs in the fray. Detailed listings of the IOMeter benchmark numbers (including IOPS and maximum response times) for each configuration are linked below:
- Synology DS415+ - iSCSI LUN (Regular Files) - 4x 4 TB / RAID-5 / 2x 1G
- Synology DS415+ - Single LUN on RAID - 4x 4 TB / RAID-5 / 2x 1G
Since the number of NAS units that we have put through this evaluation is limited, the only real point of comparison is the Seagate NAS Pro 4-bay. The ioSafe 1513+ graphs are also linked above, but it has five drives instead of the four in the DS415+. The only graphs for apples-to-apples comparison are those of the Seagate NAS Pro 4-bay units. We see advantages in terms of average access times for the Synology DS415+. This is only to be expected, given the faster clock for the Rangeley SoC in the DS415+.
As more NAS units are processed, we hope this section will provide readers with a way to quickly get an idea of the competitive performance of a particular NAS unit when it comes to iSCSI support.
Encryption Support Evaluation
Consumers looking for encryption capabilities can opt to encrypt a iSCSI share with TrueCrypt or some in-built encryption mechanism in the client OS. However, if requirements dictate that the data must be shared across multiple users / computers, relying on encryption in the NAS is the best way to move forward. Most NAS vendors use the industry-standard 256-bit AES encryption algorithm. One approach is to encrypt only a particular shared folder while the other approach is to encrypt the full volume. Synology supports only folder-level encryption for now in DSM.
On the hardware side, encryption support can be in the form of specialized hardware blocks in the SoC (common in ARM / PowerPC based NAS units). In x86-based systems, accelerated encryption support is dependent on whether the AES-NI instruction is available on the host CPU. One of the most attractive features of the Intel Rangeley platform / Silvermont cores is full hardware acceleration for all essential cryptography functions. The results, as you can see below, are consistent across all evaluated scenarios. The penalty compared to unencrypted shares is non-existent.
The write performance with encrypted shares could do with some improvement (for certain workload traces). Other than that, the higher clock for the SoC (compared to the Seagate NAS Pro) and the presence of AES-NI in the SoC (compared to its absence in the SoC used in the QNAP TS-451) enable the DS415+ to come out trumps in most of the above benchmarks.
Miscellaneous Aspects and Final Words
It is expected that most users would configure the Synology DS415+ in RAID-5 for optimal balance of redundancy and capacity. Hence, we performed all our expansion / rebuild testing as well as power consumption evaluation with the unit configured in RAID-5. The disks used for benchmarking (Western Digital WD4000FYYZ) were also used in this section. The table below presents the average power consumption of the unit as well as time taken for various RAID-related activities.
Synology DS415+ RAID Expansion and Rebuild / Power Consumption | ||
Activity | Duration (HH:MM:SS) | Avg. Power (W) |
Single Disk Init | 0:11:8 | 24.66 W |
JBOD to RAID-1 Migration | 12:6:13 | 35.43 W |
RAID-1 (2D) to RAID-5 (3D) Migration | 30:19:14 | 45.43 W |
RAID-5 (3D) to RAID-5 (4D) Expansion | 25:3:31 | 56.93 W |
RAID-5 (4D) Rebuild | 10:25:40 | 56.76 W |
The graphs below show the power consumption and rebuild duration when repairing a RAID-5 volume for the various 4-bay NAS units that have been evaluated before.
The competition for the DS415+ comes from the QNAP TS-451 and the Seagate NAS Pro 4-bay. While the QNAP unit has the same clock speeds, the TDP of the SoC is only 10 W (compared to 15 W for the Atom C2538 in the DS415+) because it is dual-core (compared to the four cores in the Atom C2538). As expected, during rebuild, the DS415+ consumes slightly more power. The Atom C2338 in the NAS Pro is clocked much lower (1.74 GHz), so it consumes a full 6 W lesser than the DS415+.
Due to its slower clock, the rebuild duration for the NAS Pro is more than that of the DS415+. That said, it does look like Synology can optimize RAID rebuild durations further, since it is handily bested by the QNAP TS-451. In terms of energy consumption for rebuild, the TS-451 is the winner (~1.8 MJ, compared ~2.0 MJ for the Seagate NAS Pro and ~2.13 MJ for the DS415+). At this point, the only downside of an Intel x86 NAS platform for prosumers and SOHO users seems to be the cost.
Concluding Remarks
The SMB / SOHO / prosumer COTS NAS market is interestingly poised. With the previous generation Atom platforms, NAS vendors had to differentiate themselves with the software. However, with their 22nm silicon, Intel has provided them with multiple options. We have already looked at QNAP using Bay Trail-D with extra focus on the multimedia transcoding and virtualization aspects. Asustor has opted to go the Haswell route, with a Core i3 CPU for the 70-series. With the DS415+, Synology has placed its bets on the Intel Rangeley platform.
The new Rangeley platform has made up for the drawbacks of the previous generation x86 platforms at this price point. Equipped with the Atom C2538, the DS415+ excels in three areas: multi-client performance, encryption capabilities and power efficiency. Synology's DSM is quite mature and it has no problems in bringing out the potential of Intel's Rangeley for the NAS market. Multi-client performance in terms of average response times is better because of the highly integrated I/O compared to other solutions (both ARM-based and some of the other x86-based solutions) which use bridge chips and have bottlenecks in connecting to the CPU. The appearance of AES-NI in the Atom-class SoCs has finally delivered power efficient encryption capabilities. Obviously, the 22 nm fabrication process as well as tight I/O integration greatly help in reducing the power consumption of the platform compared to other solutions in the market.
From a product line perspective, Synology has introduced only one Rangeley-based NAS so far (unlike Seagate which rolled out its full Rangeley lineup with 2,4 and 6 bays in one go). Prosumers / SMBs may need to hold out for a bit if they require more than four bays in a Synology NAS equipped with a Rangeley SoC.
At $600 for a diskless unit, the pricing is not unreasonable (given the premiums usually associated with Synology units). The Atom C2538 is one of the more powerful Rangeley SoCs and it helps the DS415+ pack quite a punch. Pretty much the only downside from a home consumer perspective is the absence of a hardware transcoding engine for media-centric applications. Though many multimedia apps can be installed on the DS415+, media enthusiasts are advised to go for the Synology DS415play or QNAP TS-x51 if power-efficient media serving is a primary use-case. The focus of the DS415+ is solely on the SMB / SOHO market. With the final version of DSM 5.1 around the corner, Synology seems well-placed to serve the needs of the NAS market.