Synology SA3400D 12-Bay Dual Controller NAS — main product image

Synology SA3400D 12-Bay Dual Controller NAS

Synology

Synology SA3400D 12-Bay Dual Controller NAS

Name: Synology SA3400D 12-Bay Dual Controller NAS
Brand: Synology
SKU: SA3400D

Enterprise NAS throughput over 3,500 MB/s sequential read with dual-controller failover that keeps your data accessible even when a controller node goes down.

$10,580.76*

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*Price sourced from Amazon.com. Last updated:Jul 14, 2026.Price and availability are subject to change.

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Overview

The Synology SA3400D is a 12-bay, diskless, rack-mount NAS engineered for organizations where storage availability is a hard operational requirement, not a nice-to-have. The headline specification — over 3,500 MB/s sequential read and 2,900 MB/s sequential write — positions it to serve as shared storage for data-intensive workflows: multi-stream 4K/8K video production, large-scale backup targets, database storage, or virtualization datastores. The dual-controller architecture in active-passive configuration is the defining feature: it means a single controller hardware failure does not take storage offline. Failover occurs in minutes, giving IT teams time to respond without a full production outage.

The SA3400D is built for the data center or server room, not the SMB closet. At 50 pounds and occupying significant rack depth, it is infrastructure equipment that demands proper planning — power, cooling, rack space, and high-speed networking adequate to feed its throughput capability. Storage capacity scales from 12 bays to 36 bays by adding up to two RXD1219sas SAS expansion units, allowing the platform to grow alongside increasing data volumes without forklift replacement. The five-year warranty provides enterprise-aligned coverage, and Synology's DSM operating system delivers the management depth — RAID management, snapshot scheduling, replication, and access control — expected at this tier.

Key Features

Enterprise-class Performance - Handles data-intensive applications with over 3,500/2,900 MB/s sequential read/write throughput

High Service Availability - Two controller nodes in an active-passive configuration support minute-level failover, minimizing downtime

Built-in Data Protection Solutions - Triple total storage capacity by adding up to two Synology RXD1219sas Expansion Units for 36 total drive bays

5-year warranty

Specifications

Model

SA3400D

Drive Bays

12 (base), expandable to 36

Drives Included

Diskless

Sequential Read Throughput

Over 3,500 MB/s

Sequential Write Throughput

Over 2,900 MB/s

Controller Configuration

Dual controller, active-passive

Failover Time

Minute-level

RAM

8 GB

Expansion Units Supported

Up to 2x Synology RXD1219sas

Mounting Type

Rack Mount

Dimensions

31.85 x 22.56 x 7.87 inches

Weight

50 pounds

Warranty

5 years

Pros & Cons

👍 Pros

Over 3,500/2,900 MB/s sequential read/write throughput provides the raw bandwidth needed for parallel video editing streams, large database workloads, or high-frequency backup operations.
Active-passive dual-controller failover delivers minute-level recovery from a controller hardware failure — a meaningful architectural advantage over single-controller NAS in production environments.
Expandable to 36 total bays via two RXD1219sas units, allowing storage capacity to scale with organizational growth without replacing the core unit.
Five-year warranty provides enterprise-grade support coverage aligned with typical infrastructure refresh cycles.
Rack-mount form factor integrates directly into standard data center or server room infrastructure without additional mounting hardware complexity.

👎 Cons

Ships diskless, meaning total deployment cost is substantially higher than the unit price alone once enterprise-grade SAS drives are accounted for across 12 bays.
At 50 pounds and 31.85 x 22.56 x 7.87 inches, the SA3400D requires significant rack space and two people for safe physical installation.
Base 8 GB RAM may require upgrading before deployment in high-concurrency or VM-heavy environments, adding to upfront configuration effort.
Expansion units (RXD1219sas) represent additional cost and procurement complexity for organizations that need full 36-bay capacity at launch.
Active-passive configuration means the standby controller is not serving I/O under normal conditions — organizations that need true active-active load balancing should evaluate whether this architecture fits their throughput distribution requirements.

Frequently Asked Questions

What does "active-passive dual controller" mean in practical terms for uptime?

One controller handles all I/O at a time while the second sits in standby, continuously synchronized. If the active controller fails — hardware fault, firmware crash — the passive controller takes over within minutes, not hours. For organizations where storage downtime means halted production workflows or broken SLAs, this architecture dramatically reduces blast radius from a single hardware failure compared to a single-controller NAS.

What drives are compatible, and does the SA3400D ship with drives included?

The SA3400D is diskless — drives are not included. It supports Synology-certified SAS and SATA HDDs and SSDs. For production deployments, Synology's compatibility list should be consulted; using certified drives is important for full RAID health monitoring and DSM integration. The 12-bay chassis supports 3.5" and 2.5" form factors.

How far can storage capacity be expanded, and what expansion units are required?

The SA3400D supports up to two Synology RXD1219sas Expansion Units, each adding 12 drive bays for a total of 36 bays across the system. Expansion connects via SAS, and both expansion units can be driven from either controller, maintaining high-availability coverage across the full expanded array.

What is the RAM specification, and can it be expanded?

The unit ships with 8 GB of RAM. For enterprise deployments running virtual machine workloads or high-concurrency database traffic through the NAS, reviewing Synology's RAM upgrade options for this model is recommended before deployment — the base 8 GB may become a bottleneck under intensive parallel workloads.

Does the SA3400D support 10GbE or higher networking out of the box?

Specific NIC configuration should be confirmed with Synology's product sheet, as the provided specifications do not detail onboard port speeds. Given the 3,500+ MB/s sequential throughput rating, this unit is designed for high-speed network infrastructure — 10GbE or higher connectivity is expected to be required to saturate that throughput in real deployments.