Reviewing the Synology DS1817+ with M2D17

The Synology DS1817+ and DS1517+ are announced in April 2017. The Synology DS1817+ is offered in both 2GB and 8GB RAM variants; and it officially supports up to 16GB. Three new accessories are also announced, namely: the (1) M2D17 dual M.2 SSD adapter; (2) DX517 5-bay expansion unit; and (3) E10G15-F1 10GbE NIC. We will be reviewing the Synology DS1817+ with the M2D17 dual M.2 SSD adapter for read-write cache.

The DS1817+ will be replacing my current Synology DS1515+. Meanwhile for this review, I will be using the Seagate IronWolf 10TB hard disks.

The Synology DS1817 family lineup

The DS1817 family comprise the DS1817+ (plus series) and DS1817 (value series).

DS1817+ DS1817
Processor Intel Atom C2538
Quad Core 2.4 GHz
Annapurna Labs Alpine AL-314
Quad Core 1.7 GHz
Memory 2GB (1 x 2GB)/8GB (2 x 4GB)
(Expandable to 16GB)
4GB
(Expandable to 8GB)
Encryption Yes (AES-NI) Yes
Storage 8 x 3.5"/2.5" SATA II/III; Hot Swappable
Maximum of 18 drives with DX517
Capacity Up to 80TB (8 x 10TB)
Up to 180TB with DX517 expansion unit (18 x 10TB)
Networking 4 x 1GbE
Supports Link Aggregation/Failover
2 x 1GbE
2 x 10GbE
Supports Link Aggregation/Failover
Connectors 4 x USB3.0
2 x eSATA
2 x USB3.0
2 x eSATA
PCIe 1 x Gen2 x8 slot (x4 link)
Supporting SSD adapter card or Network Interface Card
Not available
Dimensions (mm) 166 x 343 x 243 157 x 340 x 233
Weight 6.00 kg 5.31 kg
Power Consumption61.5 W (Access)
31.6 W (HDD Hibernation)
59.1 W (Access)
26.4 W (HDD Hibernation)
Noise Level22.2 dB(A) 24.2 dB(A)
SRPS$1,450 (8GB) Not available in Singapore

DS1817’s 10GbE ports

One noteworthy point is that the DS1817 has two (2) 10GbE network ports while the DS1817+ doesn’t. For the DS1817+, you can add this capability with the PCIe network adapter.

The Intel C2538 fix

One concern I had with the DS1817+ is the use of Intel C2538. Recently, devices with C2538 suffered sudden failures and required hardware fix as mitigation. Synology assured that relevant fixes or design considerations have been applied for all Synology models (utilizing C2538) since February 2017.

Avoton instead of Denverton CPU

As for the choice of Avoton over Denverton or Apollo Lake, it was mentioned that Denverton would only be released after 2017 Q2. Unfortunately, it is too late for DS1817+.

Apollo Lake is not used as it is not meant for server usage according to Intel’s classification. Perhaps future Synology models in 2018 will be using Denverton?

Unboxing the Synology DS1817+

The Synology DS1817+ is a 8-bay NAS announced in April 2017. It is offered in either 2GB or 8GB RAM variant.

The Synology DS1817+ package is pretty bulky and weighs around 7 kg. It is not as easy to lug around like the DS1515+ that I have now. I had totally under-estimated the strain that it would have on my arms when I carried it back on public bus. Reminder to self that I should have just take a cab for any NAS that has more than five (5) bays.

The contents of the DS1817+ package.

The DS1817+ package comes with:

  • Synology DS1817+ NAS;
  • Pack of screws for mounting 2.5″ drives;
  • Keys for securing the drive bays;
  • Installation guide;
  • Power cord; and
  • Two (2) Ethernet patch cords.

The power cord directly plugs into the power supply unit. There is no external ‘power brick’.

Overall Build of the Synology DS1817+

The Synology DS1817+ is an 8-bay NAS announced in April 2017. It replaces the Synology DS1815+.

The enclosure looks like an elongated version of the DS1515+. It is matte-black except for its base. The front and back of the DS1817+ are made of plastic while the rest of the body is generally made of metal.

The front of DS1817+

The front of the Synology DS1817+. On the lower right, you can spot the USB 3.0 port.

From the front, the DS1817+ looks like the DS1515+ with additional drive bays. Above the drive trays are where the power button, system indicators (status, alert, LAN) are.

There is a USB 3.0 port on the lower right corner of the DS1817+ for you to easily attach a USB storage for Synology USB Copy.

It sports the usual easy remove drive trays. They can be individually locked with the provided key.

The drive trays are designed to be easy to remove. A light press near the bottom edge of the tray releases the handle and unlatches the drive tray from the enclosure. Just grab the handle to slide the drive tray into or out of the DS1817+.

The provided keys lock the handle in place and prevents the drive tray from unlatching from the drive bays.

What’s inside the DS1817+’s drive bays? The back plane and view of the 120mm system fans.

Behind the drive trays is the SATA backplane where hard disks are attached to. The two (2) 120mm fans, at the back, draws heat away from the hard disks and out of the enclosure.

On both sides of the DS1817+ are the Synology logos which are vented for airflow as well.

The vented cutouts of Synology logo on both sides of the DS1817+ allow air to be drawn into the enclosure.

The back of the DS1817+

The back of the Synology DS1817+. The PCIe expansion slot is on the right.

At the center of the DS1817+ are two (2) 120mm system fans. To the left are the power connector and Kensington lock slot. To the right is the PCIe slot for the new Synology accessories.

To the south, from left to right, are the eSATA port, four (4) Gigabit LAN ports, reset button, three (3) USB 3.0 ports and eSATA port.

The M2D17 dual M.2 SSD PCIe adapter

The Synology M2D17 dual M.2 SSD adapter is compatible with the DS1817+. It allows you to add two M.2 SSD to the DS1817+ without sacrificing any disk bays for SSD cache!

The M2D17 is a M.2 SSD adapter that allows you to add SSD cache capability to your Synology NAS without sacrificing any of the existing drive bays. In the past, you will need to allocate two drive bays if you need read-write cache. For a 5-bay NAS, you will be left with 3 bays for your main storage.

The M2D17 supports two 2242/ 2260/ 2280 form-factor M.2 SSDs from various vendors. Do check out the hardware compatibility list for the supported make and model.

Synology M2D17 Technical Specifications
Applied Models DS1517+
DS1817+
PCIe Interface PCIe 2.0 x8
Supported Form Factor 2242, 2260, 2280
Bracket Height Low-profile
Warranty 3 years
The package comes with the M2D17 adapter, a pack of screws and a pack of spacers.

Within the Synology M2D17 package, you will find:

  • The low-profile M2D17 M.2 SSD PCIe adapter;
  • A pack of screws; and
  • A pack of spacers

On the right are two slots for 2242/ 2260/ 2280 form-factor M.2 SSDs. Do note that M.2 NVMe/AHCI PCIe SSD is not supported.

The M.2 SSDs

The SSD read-write cache feature requires two SSDs in RAID 1 configuration. Hence, we gotten two different but similar capacity M.2 SSDs, namely:

  1. Samsung 850 Evo 250GB
  2. Western Digital Blue 250GB

What are the pros and/ or cons of using different SSDs?

  • Pro. Don’t suffer from concurrent failures due to design flaws.
  • Con. Degraded RAID 1 performance if SSDs have different performance

Why are the SSDs configured in RAID 1 in a read-write cache? The cache is the first location to fetch or deposit your data and it will reach out to the regular disks if the desired contents cannot be located in the cache. For write caching, any failure in the cache storage will result in data loss and thus RAID 1 is required to protect written data. On the other hand for read caching, the data are still available in the regular disks thus RAID 1 is not required.

Samsung 850 EVO 250GB M.2 SSD

Samsung 850 EVO 250GB M.2 2280 SSD for DS1817+’s read-write SSD cache!
Samsung 850 EVO 250GB M.2 SSD Specifications
Controller Samsung MGX
Interface SATA 6GB/s
Memory Samsung V-NAND
Cache Memory 512 MB Low Power DDR3
Sequential Read Up to 540 MB/s
Sequential Write Up to 520 MB/s
Random Read (4KB, QD32) 97,000 IOPS
Random Write (4KB, QD32) Up to 89,000 IOPS
Warranty 5 Years or 75 TBW
Samsung 850 EVO 250GB M.2 2280 SSD for DS1817+’s read-write SSD cache!

Western Digital Blue 250GB M.2 SSD

Western Digital Blue 250GB M.2 2280 SSD for DS1817+’s read-write SSD cache!
WD Blue 250GB M.2 SSD Specifications
Controller Marvell 88SS1074
Interface SATA 6GB/s
Memory SanDisk 15nm TLC
Cache Memory 256 MB Low Power DDR3
Sequential Read Up to 540 MB/s
Sequential Write Up to 500 MB/s
Random Read (4KB, QD32) 97,000 IOPS
Random Write (4KB, QD32) Up to 79,000 IOPS
Warranty 3 years or 100 TBW
Western Digital Blue 250GB M.2 2280 SSD for DS1817+’s read-write SSD cache!

Side-by-side comparison of Samsung 850 EVO and WD Blue

Samsung 850 EVO WD Blue
Controller Samsung MGX Marvell 88SS1074
Interface SATA 6GB/s
Memory Samsung V-NAND SanDisk 15nm TLC
Cache Memory 512 MB Low Power DDR3 256 MB Low Power DDR3
Sequential Read Up to 540 MB/s
Sequential Write Up to 520 MB/s Up to 500 MB/s
Random Read (4KB, QD32) 97,000 IOPS
Random Write (4KB, QD32) Up to 89,000 IOPS Up to 79,000 IOPS
Warranty 5 Years or 75 TBW 3 Years or 100 TBW

At this juncture, both SSDs’ performance looks great. In the later part of this review, we will be benchmarking their performance under some synthetic workload.

The souped-up DS1817+

We will be upgrading the DS1817+ to 16GB RAM and enable its SSD read-write cache.

Installing additional RAM

The DS1817+ has two (2) RAM slots and officially supports up to 16GB (dual channel). We got the Crucial 16GB RAM kit (2 x 8GB).

The RAM slots are located on the underside of the DS1817+. The RAM upgrading process is straightforward as we just have to remove a couple of screws to access the slots. Installing the new RAM modules took last than 10 minutes.

Upgrading the Synology DS1817+’s RAM to 16GB!
Upgrading the Synology DS1817+’s RAM to 16GB!
Upgrading the Synology DS1817+’s RAM to 16GB!

The Synology DS1817+ with 16GB RAM! The additional RAM will come in useful for the new virtualization feature.

Installing the SSDs

The Synology M2D17 supports up to two (2) M.2 SSDs. We will be installing the M2D17 with Samsung EVO 850 and Western Digital Blue M.2 SSDs into the Synology DS1817+.

Installing the M2D17 requires you to remove the DS1817+’s enclosure to access the PCIe slot. Previously, this area of the Synology NAS used to be where the RAM slots are located.

Just in case you are wondering if you can use the M2D17 with SSDs as part of your regular storage volume. Nope, you cannot. You will have to tinker with the mdadm to do so and risk losing your data (plus su.

These two M.2. SSDs are pairing up for read-write SSD cache on the Synology DS1817+.
The M2D17 adapter populated with two 250GB M.2 SSDs for read-write caching on the DS1817+.
Installing the M2D17 dual M.2 SSD adapter.
Installing the M2D17 dual M.2 SSD adapter.

Configuring the SSD Cache

For those who are new to SSD cache just like me, the process of creating SSD cache is just a matter of following the Synology SSD Cache Creation Wizard.

There is also a SSD Cache statistics dashboard to view the status of the cache usage and hit rate.

Let’s create a SSD cache. It is created via the Storage Manager.
Since we have got two SSDs, let’s create a read-write cache.
Using both the Samsung 850 EVO and WD Blue for the read-write cache.
Warning message when I attempt to set up SSD read-write cache using the Samsung 850 EVO and WD Blue M.2 SSDs.
For SSD read-write cache, you will need two SSDs in RAID 1 configuration.
The amount of RAM required for every 1GB of SSD cache.
Last step before the SSD cache is created.
Finalizing the SSD Cache setup on the DS1817+.
SSD Cache is almost set up on the DS1817+.
SSD Cache is ready to be used. Benchmarking the speed next!
Read-write SSD cache enabled on the DS1817+.

Benchmark – The SSDs

We are interested in a couple of things with this new DS1817+ and M2D17:

  • How well does SSDs perform through the M2D17?
  • How much performance gain does SSD cache has on the volume?

To find out, we will be benchmarking this setup with 70% reads and 30% writes in 8KB blocksize to uncover its reading and writing throughput and latency. These benchmarks will be conducted using Fio.

Fio, or Flexible IO, is a versatile Input Output generator that is often used to benchmark the IO subsystem.

Another benchmarking tool that we will be using is hdparm which measures the direct reads and cached reads from storage media.

Benchmarking the SSD from DS1817+

These two M.2. SSDs are pairing up for read-write SSD cache on the Synology DS1817+.

We will be using both Fio and hdparm to benchmark the performance of Samsung 850 EVO and Western Digital Blue in the DS1817+. This benchmark is important as it is part of the pipeline before data get sent over the network so we don’t wish to see any bottlenecks between the SSDs and DS1817+.

  • Fio will be generating workloads comprising 70% reads and 30% writes (rwmixread=70) in 8KB blocksize (bs=8k) for 60 seconds. The order of reads and writes will be randomized (rw=rwrand). There will be 16 IO units in queue (iodepth=16) to the device at any point during the test to keep it fully occupied.
  • hdparm will perform sequential direct reads and cached reads test.

Both tools will run directly against the storage devices (/dev/nvc1, /dev/nvc2) on the DS1817+. This will exclude filesystem’s performance.

Summary of SSDs Benchmark

The benchmark results of Samsung 850 EVO 250GB M.2 SSD and Western Digital Blue 250GB M.2 SSD are as follow.

Read (MB/s)Write (MB/s)
WD Blue 250GB M.2 SSD 113.36 48.64
Samsung 850 EVO 250GB M.2 SSD 179.24 76.83
Avg Read Latency (ms) Max Read Latency (ms) Avg Write Latency (ms) Max Write Latency (ms)
WD Blue 250GB M.2 SSD 12.35 410.14 12.31 409.95
Samsung 850 EVO 250GB M.2 SSD 7.82 402.14 7.76 401.94
Cached Reads (MB/s) Buffered Reads (MB/s) Read IOPS Write IOPS
WD Blue 250GB M.2 SSD1,873.26 354.36 14,510 6,225
Samsung 850 EVO 250GB M.2 SSD1,949.15 359.65 22,942 9,843

From the results, we can see that the Samsung 850 EVO 250GB M.2 SSD performs noticeably better than the WD Blue 250GB M.2 SSD.

In both read and write operations, the Samsung 850 EVO 250GB M.2 SSD exhibited better throughput, lower latency and higher IOPS when compared to the Western Digital Blue 250GB M.2 SSD.

Benchmark – Storage Volume with SSD Cache

The statistics of the SSD cache.

We will also be using Fio to benchmark the performance of the DS1817+ under the following scenarios:

  • SSD cache is not enabled;
  • SSD read cache is enabled; and
  • SSD read-write cache is enabled.

The SSD cache works by moving frequently accessed data onto the faster storage (i.e. SSD) so that the system need not wait for the slower storage (i.e regular disks) to respond.

Hence, we will go through a phrase of preconditioning before the actual benchmark test:

  • Preconditioning. 5 sets of writing and reading from pre-prepared files to allow data to be cached;
  • Benchmark. 1 set of writing and reading from the same pre-prepared files.

For each sets, the IO workload will be 70% reads and 30% writes in 8KB blocksize for 60 seconds. The order of reads and writes are randomized.

SSD Cache Benchmark Summary

The benchmark results of the DS1817+ under various SSD cache configurations are as follow.

Read (MB/s)Write (MB/s)
Without SSD Cache 4.4 1.88
SSD Read Cache – WD Blue 250GB M.2 8.75 3.79
SSD Read Cache – Samsung 850 EVO 250GB M.2 9.27 3.96
SSD Read-write Cache 16.95 7.24
Avg Read Latency (ms) Max Read Latency (ms) Avg Write Latency (ms) Max Write Latency (ms)
Without SSD Cache 201.51 1,299 189.17 1,295
SSD Read Cache – WD Blue 250GB M.2 34.92 750.63 248.44 1,529
SSD Read Cache – Samsung 850 EVO 250GB M.2 32.37 427.68 239.18 831
SSD Read-write Cache 41.81 2,142.9 74.57 4,806.8

Firstly, don’t be alarmed by the low throughput figures. It appears that fio’s workload and measurement reflected a lower throughput for tests on the storage volume. Our objective is to measure the difference in performance under different SSD cache configurations.

Across the tests, it is clear that the both reading and writing speeds are greatly improved when SSD cache is enabled.

Findings when SSD read cache is enabled

When SSD read cache is enabled, the average latency for read operations drastically dropped. However, the average latency for write operations increased slightly.

We also observed that the performance is better when the Samsung 850 EVO is used as the cache.

Findings when SSD read-write cache is enabled

When SSD read-write cache is enabled, the average latency for writing operation is reduced.

Read 50th Percentile (ms) Read Std Dev (ms) Write 50th Percentile (ms) Write Std Dev (ms)
Without SSD Cache 165.00 109.34 167.00 110.68
SSD Read Cache – WD Blue 250GB M.2156.8046.56221.00146.68
SSD Read Cache – Samsung 850 EVO 250GB M.2 144.00 38.46255.00116.56
SSD Read-write Cache 26.24 43.93 35.58 173.93

We also observed the maximum latency went off the chart during the tests. But when we delved into the statistics, we observed that the maximum readings are just some statistical outliers. The 50th percentile and standard deviation looks pretty ok.

Benchmark – Virtual Machine’s Performance with SSD Cache

The Ubuntu 16.04 LTS virtual machine on the DS1817+.

One of the queries we get is whether will the virtual machines (under Synology Virtual Machine Manager) benefit from the SSD cache on the Synology NAS?

To find out whether Synology Virtual Machine Manager will benefit from SSD cache, we will be using Fio to benchmark the virtual machine’s performance on DS1817+. Fio will be running within the virtual machine under the following scenarios:

  • DS1817+’s SSD cache is not enabled;
  • DS1817+’s SSD read cache is enabled; and
  • DS1817+’s SSD read-write cache is enable.

We will be using a Ubuntu 16.04 LTS Linux OS as the virtual machine for this benchmark. Why not a Microsoft Windows OS? Well, it is to standardise the testing tool – Fio.

The virtual machine have the following configuration:

  • Ubuntu 16.04 LTS
  • 2 vCPU
  • 8GB RAM
  • 50GB vHDD (Virtual disk controller: virtio)

The SSD cache works by moving frequently accessed data onto the faster storage (i.e. SSD) so that the system need not wait for the slower storage to respond.

Hence, we will go through a phrase of preconditioning before the actual benchmark test:

  • Preconditioning. 5 sets of writing and reading from the pre-prepared files to allow data to be cache onto the SSD cache;
  • Benchmark. 1 set of writing and reading from the same pre-prepared files.

For each sets, the IO will be 70% reads and 30% writes in 8KB blocksize for 60 seconds. The order of reads and writes are randomized.

Virtual Machine’s Performance SSD Cache Benchmark Summary

The benchmark results from the virtual machine under various SSD cache configurations are as follow.

Read (MB/s)Write (MB/s)
Without SSD Cache 2.56 1.13
SSD Read Cache – WD Blue 250GB M.2 3.73 1.62
SSD Read Cache – Samsung 850 EVO 250GB M.2 3.75 1.63
SSD Read-write Cache 10.88 4.67
Avg Read Latency (ms) Max Read Latency (ms) Avg Write Latency (ms) Max Write Latency (ms)
Without SSD Cache 342.72 2,999.3 329.68 2,998.3
SSD Read Cache – WD Blue 250GB M.2 237.32 3,707.3 224.54 3,356.9
SSD Read Cache – Samsung 850 EVO 250GB M.2 233.89 3,619.3 227.29 3,618.8
SSD Read-write Cache 81.56 831.56 77.46 831.14
Read IOPSWrite IOPS
Without SSD Cache 327 144
SSD Read Cache – WD Blue 250GB M.2 477 207
SSD Read Cache – Samsung 850 EVO 250GB M.2 480 208
SSD Read-write Cache 1392 597

Findings when SSD read cache is enabled

When SSD read cache is enabled, both the virtual machine’s read and write latencies by the noticeably dropped. Both read and write IOPS improved with reads having the most improvement. Both read and write throughput improved.

Findings when SSD read-write cache is enabled

When SSD read-write cache is enabled, we observed great reduction in terms of read and write latencies. There is approximately 280% to 400% reduction in reading and writing latencies.

Similarly, stark improvement in both throughput and IOPS were also observed. Input/ Output per second (IOPS) also improved as much as 400%.

Conclusion

The DS1817+ is a another great NAS from Synology as you can enable SSD cache without sacrificing any of the drive bays.

It is a good choice if you are looking to upgrade from a 4 or 5 bays NAS. However, the benefits might be marginal if you are upgrading from the DS1815+ unless you are looking enabling SSD cache via the M2D17 dual SSD adapter.

The reading and writing performance definitely improved when the SSD cache is enabled using the Samsung 850 EVO and Western Digital Blue M.2 SSDs. The network transfer should also improve correspondingly.

For those who are running virtual machines via the Synology Virtual Machine Manager, you will be pleasantly surprised by the performance boost that SSD read-write cache will bring. In our benchmark, read and write latencies reduced as much as 400% and IOPS improved by almost the same factor.

Lastly, my advice to potential M2D17 adopters is to use similar performance SSDs for read-write cache. I suspect the latency spikes observed while benchmarking the performance of read-write are due to the difference in the individual SSDs’ performance. As mentioned earlier, the spikes are statistical outliers as the median and standard deviations looks pretty ok.

4 thoughts on “Reviewing the Synology DS1817+ with M2D17

  • July 28, 2017 at 11:16 am
    Permalink

    drool ~~~~

  • August 31, 2017 at 4:23 am
    Permalink

    i’ve been looking at upgraded NAS offerings. this seems like a great choice, my workflows are mostly IOPS limited, so this would represent a significant increase in performance and a significant decrease in keyboard smashing stress.

  • January 10, 2018 at 10:50 am
    Permalink

    Good review. Do you know if it possible to use an M.2 SSD installed in the M2D17 card as an extra storage device? Such as using it to run all your app’s etc (docker, virtual machines…) instead of running them off the array. I currently use slot 8 with an SSD installed for this purpose

  • January 10, 2018 at 12:32 pm
    Permalink

    Hi Darren,

    Unfortunately, we can’t use the SSD on the M2D17 as storage volume. It will just appear as SSD cache.

Comments are closed.