Synology DS420+ 4-Bay NAS DiskStation (Diskless)

Name: Synology DS420+ 4-Bay NAS DiskStation (Diskless)
Brand: Synology
SKU: DS420+

Overview

The Synology DS420+ is a four-bay NAS centered on an Intel dual-core processor with AES-NI hardware encryption — a specification that separates it from ARM-based competitors when it comes to encrypted volume throughput and compute-intensive tasks like photo indexing and container workloads. The rated 226 MB/s sequential read and 225 MB/s sequential write speeds describe the storage subsystem's ceiling; what makes those numbers usable rather than theoretical is the dual M.2 2280 NVMe SSD cache slots, which sit entirely outside the four primary drive bays. SSD cache in front of spinning disks compresses the latency gap dramatically for workloads with repeated access patterns — file serving and database applications see the most consistent benefit.

In practical terms, the DS420+ is aimed at power users and small teams who want NAS functionality beyond simple file storage: Synology Photos with AI subject recognition, Surveillance Station for IP camera recording, Docker-based self-hosted applications, and virtual machine hosting all run on DSM with genuine stability. The 2GB DDR4 base is adequate for lighter workloads but should be treated as a starting point — the upgrade path to 6GB is inexpensive and recommended for anyone deploying more than two or three active applications simultaneously. The platform's long-term value is in DSM itself: Synology's software track record means the DS420+ receives meaningful feature updates years after purchase, making it a more durable investment than comparable hardware running less-maintained firmware.

Key Features

Two built-in M.2 2280 NVMe SSD slots permit cache acceleration without occupying storage drive bays.

Intel dual-core processor with AES-NI hardware encryption engine; over 226 MB/s sequential read and 225 MB/s sequential write throughput.

2 GB DDR4 memory (expandable up to 6 GB)

Average 15% performance boost to photo indexing and other computing-intensive operations, as well as database response time.

By default, two camera licenses are installed; extra licenses can be purchased (CLP1, CLP4, or CLP8)

Specifications

Drive Bays

4 (3.5" / 2.5" SATA)

M.2 SSD Slots

2 x M.2 2280 NVMe (cache only)

Processor

Intel Dual-Core with AES-NI hardware encryption

Memory

2 GB DDR4 (expandable to 6 GB)

Sequential Read Throughput

>226 MB/s

Sequential Write Throughput

>225 MB/s

Storage Interface

SATA

Operating System

Synology DiskStation Manager (DSM)

Camera Licenses (included)

2 (expandable via CLP1, CLP4, CLP8)

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Pros & Cons

👍 Pros

Two dedicated M.2 NVMe SSD cache slots accelerate read/write performance without consuming any of the four primary drive bays — a meaningful design advantage over NAS units that sacrifice storage capacity for cache.
226 MB/s sequential read throughput, backed by Intel's AES-NI hardware encryption engine, handles encrypted volume performance without the CPU penalty that plagues ARM-based alternatives.
DSM (DiskStation Manager) is one of the most mature and feature-complete NAS operating systems available — Docker, virtual machines, Surveillance Station, and Synology Photos all run natively.
2GB DDR4 base memory with expandability to 6GB gives a real upgrade path for users whose workloads grow over time.
Intel dual-core processor provides the compute baseline needed for photo indexing, transcoding, and multi-application operation without significant queuing.

👎 Cons

Standard gigabit Ethernet limits real-world throughput to approximately 125 MB/s regardless of drive or cache configuration — realizing the 226 MB/s rated speed requires network infrastructure upgrades.
2GB base RAM is modest for running multiple active applications simultaneously; users who deploy Docker containers alongside Surveillance Station and Photos will want to upgrade immediately.
Ships diskless with no drives and no M.2 cache SSDs included — full build cost is substantially higher than the unit price suggests.
Four bays limits raw capacity expansion; large media libraries or backup repositories that need 40TB+ will hit a ceiling without external storage.

Frequently Asked Questions

What drives do I need to buy, and how many does the DS420+ support?

The DS420+ ships diskless — no hard drives included. It accepts up to four 3.5" or 2.5" SATA drives in its main bays. Drive selection depends on your capacity and redundancy needs; Synology publishes a compatibility list, and drives on that list are validated for reliable operation under DSM.

What does the M.2 NVMe SSD cache actually do for performance?

The two M.2 2280 NVMe slots are dedicated to SSD cache acceleration — they accelerate read and write access to frequently accessed data by serving as a fast buffer in front of the slower spinning drives. Critically, they do not occupy any of the four drive bays, so you get cache performance without sacrificing storage capacity.

Can I expand the memory beyond 2GB?

Yes — the DS420+ ships with 2GB DDR4 but is expandable to 6GB. A RAM upgrade meaningfully improves performance for memory-intensive workloads like running multiple Docker containers, virtual machines, or heavy Synology Photos indexing.

What is the real-world sequential throughput, and what limits it?

Synology rates the DS420+ at over 226 MB/s sequential read and 225 MB/s sequential write. The bottleneck in most home setups is the 1GbE network interface, which caps practical throughput at ~125 MB/s — to approach the rated speeds, a 2.5GbE or 10GbE network adapter upgrade or direct USB 3.0 transfer is needed.

Does the DS420+ support surveillance camera recording out of the box?

Yes — two Surveillance Station camera licenses are included by default. Additional licenses are available as CLP1, CLP4, or CLP8 packs for expanding beyond two cameras.