Synology DS3018xs Review

Synology unveiled its first 6-bay NAS, the DS3018xs, at Cebit in March 2017. It supports the optional dual M.2 SSD adapter card or 10GbE NIC for high-IOPS system cache and ultra-fast data transmission respectively. It can support up to 30 drives when used with two DX1215 expansion units. The DS3018xs sports a much newer dual-core 2.2GHz Celeron D1508 CPU. The XS series comes with 5-year warranty and advance hardware replacement through Synology Replacement Service (SRS).

Earlier this year, Synology also released the DS1817+ and DS1517+ which uses the 2.4GHz Atom C2538. Prosumers looking for a NAS might be tied between the DS1817+ and DS3018xs. Does their price difference warrant for the CPU, warranty duration and product replacement support? Compared to the DS1817+, the DS3018xs seems to be an energy guzzler.

DS3018xs DS1817+
Processor Intel Pentium D3018
Dual Core 2.2 GHz (2.6 GHz turbo)
Intel Atom C2538
Quad Core 2.4 GHz
Memory 8GB ECC
(Expandable to 32GB ECC)
2GB (1 x 2GB)/8GB (2 x 4GB)
(Expandable to 16GB)
Encryption Yes (AES-NI)
Storage 6 x 3.5"/2.5" SATA II/III; Hot Swappable
Maximum of 30 drives with DX1215
8 x 3.5"/2.5" SATA II/III; Hot Swappable
Maximum of 18 drives with DX517
Capacity Up to 72TB (6 x 12TB)
Up to 360TB with DX1215 expansion unit
(18 x 12TB)
Up to 96TB (8 x 12TB)
Up to 216TB with DX517 expansion unit
(18 x 12TB)
Networking 4 x 1GbE
Supports Link Aggregation/Failover
Connectors 3 x USB3.0
2 x Infiniband
4 x USB3.0
2 x eSATA
PCIe 1 x Gen3 x8 slot (x8 link)
Supporting SSD adapter card or Network Interface Card
1 x Gen2 x8 slot (x4 link)
Supporting SSD adapter card or Network Interface Card
Dimensions (mm) 166 x 282 x 243166 x 343 x 243
Warranty 5-year 3-year
(Optional 2-year extended warranty available)
SRS Yes No
Weight 5.2 kg 6.0 kg
Power Consumption126.89 W (Access)
56.92 W (HDD Hibernation)
61.5 W (Access)
31.6 W (HDD Hibernation)
System Fan 2 x 92mm 2 x 120mm
Noise Level25.5 dB(A) 22.2 dB(A)
SRPS$1,968 (8GB) S$1,450 (8GB)

Taking a closer look at DS3018xs

The iconic brown packaging for Synology products. Inside is the Synology DS3018xs!

Like the most-if-not-all (recent) Synology products, the DS3018xs also has the iconic brown carton box packaging. I am not complaining as I am assuming that lesser cost going into shipping packaging equates to more for the product itself.

The back of the DS3018xs’s packaging. The usual sticker highlighting the core features of the product.

The back of the packaging has a sticker highlighting the main features of the DS3018xs.

The Synology DS3018xs, 2 x Ethernet patch cords (1 GbE), power cable, drive mounting screws, tray locking keys and quick installation guide.

So what’s included? You will find the following:

  1. Synology DS3018xs 6-bay NAS;
  2. 2 x Ethernet patch cord;
  3. Power cable;
  4. A packet of mounting screws;
  5. A set of drive tray locking keys;
  6. Quick installation guide.

The Synology DS3018xs

Synology’s first 6-bay NAS with Pentium CPU. There is a USB 3.0 port at the front for easy access to the ‘USB Copy’ feature.

The DS3018xs isn’t as wide as the DS1817+ but they have similar height and depth. It is matte-black for the entire enclosure except for its bottom. The front bezel and back panel is made of plastic while the remaining part of the enclosure is metal.

The front of the DS3018xs

Near the top of the DS3018xs are where the power button and status indicators are located. On the lower right is the USB 3.0 port.

The 6 drive bays are accessible from the front. The drive trays can be individually locked using the included key. Above the drive bays are where the power button and system indicators (status, alert, LAN) are located.

On the lower right hand corner of the DS3018xs is a USB3.0 port for you to attach portable storage media for purposes like automated backup via Synology USB copy.

The backplane inside the DS3018xs.

Behind the drive trays is the backplane where the SATA drives are attached to. The two 92mm system fans draw the heat away from the disks and push it out from the back of the DS3018xs.

The back of the Synology DS3018xs

The power socket, Kensington lock slot, two infiniband ports, four Gigabit Ethernet ports, two USB 3.0 ports, two 92mm system fans and PCIe slot.

At the center of the DS3018xs are the exhaust for the system fans.

From the left to right anti-clockwise are the power connector, Kensington lock slot, infiniband expansion port, four Gigabit Ethernet ports, two USB 3.0 ports, infiniband expansion port and PCIe expansion slot.

Boosting DS3018xs’s RAM

The DS3018xs supports up to 32GB RAM which is great for Synology’s Virtual Machine Manager. However, it requires ECC RAM instead of the regular ones (Non-ECC) used in the plus series (like the DS1817+).

DDR4 16GB ECC RAM module from Synology.
DDR4 16GB ECC RAM module from Synology.

For those who are interested, the RAM specification required by the DS3018xs is DDR4-2133 ECC unbuffered SO-DIMM 260pin 1.2V. Synology do sell these RAM upgrade modules under part number “RAMEC2133DDR4SO-16G”. In the market, there doesn’t seem to be a lot of retailers selling 16GB DDR4 SO-DIMM ECC RAM modules. The Synology RAM module that I got comes with 5-year warranty.

Installing the additional RAM stick into the DS3018xs is pretty straight-forward. Simply pop open the bottom panel and install the additional stick. The DS3018xs has got two RAM slots, allowing you to upgrade it to 32GB (2 x 16GB).

The cover to access the RAM slots.
The DS3018xs comes included with a 8GB ECC RAM module.
Installed the additional 16GB, boosting the DS3018xs’s RAM to 24GB!

After the various tests, the DS3018xs will be running 24GB RAM to support the containers and virtual machines in Docker and Virtual Machine Manager respectively.

Synology DS3018xs and DS1817+ side by side

Both the DS3018xs and DS1817+ are released this year and some might be curious if they look different. Well, I can assure you that Synology NAS looks pretty similar across the different models of the plus and XS series.

The Synology DS3018xs and DS1817+ side by side. The 6-bay and 8-bay have the same height and depth.

They actually look pretty similar, just a difference of two drive bays.

The back of the DS3018xs and DS1817+. Differences are the size of the system fans and expansion port.

The back panel looks slightly different as they have different system fans and expansion ports. The DS3018xs comes with 92mm system fans and infiniband expansion ports while the DS1817+ has 120mm system fans and eSATA expansion ports.

The silver looking slot on the right of the DS1817+ is the M2D17 dual M.2 SSD adapter that I have installed. I am using SSD cache on the DS1817+.

DS3018xs’s Pentium D3108 versus DS1817+’s Atom C2538

The NAS is just simply another computer (or server) on the network providing storage resources to other clients. Just like any other computers, it comprise CPU, RAM and storage.

Today’s modern CPU (i.e. Atom, Pentium, Annapurna, etc.) can handle most of the workloads generated by typical home users, prosumers and (potentially) SMB (small and medium-sized businesses). However, the need for a good CPU arises when used in an environment with large number of users concurrently accessing the NAS as the CPU impacts overall IOPS. Yes, IOPS is not just a matter of storage media (e.g. hard disk, solid state drives).

Each IO may take 1 to 2 CPU cycles to handle the interrupt instruction and setup the data transfer. If you factor in the overheads like RAID, cache checks, de-duplication, compression, etc., each IO may incur additional CPU cycles.

Traditionally with hard disks, the hard disk’s IO is often the bottleneck. However, this situation is no longer true with today’s flash storage or SSD – The CPU has became bottleneck. Hence, having good CPU is crucial for high IOPS.

So lets see if the CPU in DS3018xs and DS1817+ performs differently through two tests:

  1. Video transcoding using ffmpeg; and
  2. Fio storage benchmark with similar hard disks.

Comparing CPU performance of DS3018xs and DS1817+ using ffmpeg

We will measure the time taken to transcode a 4K video to lower resolution as a proxy to measure the performance of DS3018xs’s Pentium D3108 and DS1817+’s Atom C2538. Video transcoding is a CPU intensive task and it should stress the CPU.

Why ffmpeg and not other CPU benchmarking tool? We used ffmpeg because it is available on Synology NAS (part of DS Video) and it should have been optimised to run on Synology NAS.

The video that we used is a 4K UHD video of fireworks at Taipei 101 (link to video). We will be measuring the time taken to transcode the 3840×2160 video to 1280×740 with the following command:

Better CPUs should take shorter time to complete the video transcoding.

Comparing CPU performance of DS3018xs and DS1817+ using Fio

We will be comparing the CPU’s impact on storage performance using Fio. Both DS3018xs and DS1817+ are equipped with RAID 1 group comprising Seagate IronWolf 10TB and Seagate IronWolf 6TB. Do note that hard disks have their own IOPS limits. In this test, we will be testing whether the overall NAS’s IOPS is affected by CPU.

DS3018xs DS1817+
RAID Level 1 1
Disk 1 Seagate IronWolf 10TB Seagate IronWolf 10TB
Disk 2 Seagate IronWolf 6TB Seagate IronWolf 6TB

The IO workload will be 70% reads and 30% writes in 8KB blocksize for 60 seconds. The order of reads and writes are randomized. The fio command is as follow:

Better CPUs should reflect higher IOPS and transfer rates.


The time taken (shorter is better) to transcode the 4K UHD video by the DS3018xs and DS1817+ are:

DS3018xs DS1817+
real (secs) 176.121 268.551
user (secs) 685.547 1,054.244
sys (secs) 1.451 3.020
Time taken by DS3018xs to transcode the 4K video.
Time taken by DS1817+ to transcode the 4K video.

From the video transcoding test results, DS3018xs’s D3108 CPU is approximately 30% faster than DS1817+’s C2538.

The results for the storage performance test are:

DS3018xs DS1817+
Read bandwidth (KB/s) 5,596.3 5,289.5
Read IOPS 699 661
Read Average Latency (ms) 151.66 158.975
Write bandwidth (KB/s) 2,388.3 2,269.1
Write IOPS 298 283
Write Average Latency (ms) 179.892 191.362

In terms of storage performance, the DS3018xs performed better than the DS1817+. I will probably run another test with SSD caching to see if it widens the gap between the two NAS as SSD have higher IOPS than hard disk.


I would say I am happy with Synology’s first 6-bay NAS – DS3018xs. The Intel Pentium D1508 CPU is noticeably faster than the Intel Atom C2538 used by the DS1817+ as observed in the video transcoding and storage performance tests.

The refreshed CPU and support for 32GB RAM allows the Synology DS3108xs to better handle Synology’s virtualization app (i.e. Virtual Machine Manager, Docker).

My take on the Synology DS3018xs? It is great for prosumer who often toy with virtual machines for their development or testing work; or those who uses Plex alot for video transcoding. Of course, it is also great for those offices with CPU intensive workloads.

2 thoughts on “Synology DS3018xs Review

  • December 31, 2017 at 7:04 pm

    Excellent pros / cons analysis of these two prosumer NAS. I much prefer the idea of having a Celeron / Xeon-D processor with ECC memory for my data (it used to be branded Xeon-D). But I don’t need ultimate CPU speed for my usage. And the extra 2 bays, lower at idle power consumption and lower price tip me towards the DS1817+.

  • January 3, 2018 at 10:58 am

    Thanks for the comment! I am still trying to figure out the workloads suitable for the DS3018xs. At the moment, virtual machine manager runs pretty well on this NAS!

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