4-Bay vs 2-Bay NAS Devices in 2026: Key Differences
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Choosing between a 4-Bay vs 2-Bay network attached storage device depends on your capacity needs and setup type. Both Synology and Buffalo units provide centralized file storage and backup capabilities for your data. The main difference lies in the form factor and drive count. The Synology unit is a 4-bay expansion unit designed for rack mounting, while the Buffalo model is a standalone 2-bay NAS with pre-installed drives for home use.
Key differences
| Aspect | Synology 4-Bay Rackmount Expansion Unit | Buffalo LinkStation 220 4TB 2-Bay NAS |
|---|---|---|
| Number of Bays | 4-Bay | 2-Bay |
| Included Storage | Diskless | 4TB |
| Form Factor | Rackmount (44 mm height) | Desktop (8.82 inches height) |
| RAID Support | not listed | RAID 0, RAID 1 |
| Target User | Expansion/Enterprise | Home Users |
Which one should you choose?
Choose Synology 4-Bay Rackmount Expansion Unit if
- You need to expand existing storage by adding a 4-bay unit to a rack.
- You prefer a diskless chassis to install your own drives for maximum flexibility.
- You require a low-profile 44 mm height unit for 2-post or wall mount racks.
Choose Buffalo LinkStation 220 4TB 2-Bay NAS if
- You want a complete solution with 4TB of storage included right out of the box.
- You need a standalone desktop unit that connects directly to your router for home use.
- You require built-in RAID 0 or RAID 1 options for data redundancy without extra configuration.
Verdict: The Synology RX418 is the right choice if you are expanding an existing NAS setup and need rack-mountable space. The Buffalo LinkStation 220 suits home users who want a ready-to-use desktop NAS with pre-installed drives. Your decision hinges on whether you need expansion hardware or a complete standalone storage system.
4-Bay vs 2-Bay NAS Comparison
Number of Bays
The Synology RX418 offers four drive bays, providing a higher potential storage ceiling for your data. This expansion unit is diskless, meaning you must purchase drives separately to populate all four slots. In contrast, the Buffalo LinkStation LS220 features two drive bays and comes with 4TB of pre-installed storage. This configuration gives you immediate usable space, typically set to RAID 1 for redundancy. If you need raw expansion potential for large media libraries, the four-bay design offers more flexibility. The two-bay model provides a simpler, ready-to-use solution with included drives.
Form Factor
Physical size dictates where you can place your storage device. The Synology RX418 is a rackmount expansion unit measuring 1.73 inches in height, 11.4 inches in width, and 17 inches in length. It weighs 9.44 pounds and is designed to fit into 2-post racks or wall mounts. The Buffalo LinkStation LS220 is a desktop unit, significantly smaller at 8.82 inches in height, 10 inches in width, and 5.04 inches in length. It weighs only 1 pound. The Synology unit requires rack infrastructure, while the Buffalo unit sits easily on a desk or shelf.
Included Storage
Storage availability affects your initial setup time. The Synology RX418 is sold as a diskless unit, offering zero included storage. You are responsible for sourcing and installing four hard drives to achieve any capacity. The Buffalo LinkStation LS220 includes 4TB of storage, configured as two 2TB drives. This allows for immediate operation upon unboxing. The Buffalo unit ships in RAID 1, providing 2TB of useable capacity for redundancy, or RAID 0 for the full 4TB. The Synology model offers no pre-installed media, requiring additional investment and effort.
RAID Support
Data protection and performance configurations vary by manufacturer. The Buffalo LinkStation LS220 explicitly supports RAID 0 and RAID 1. RAID 0 allows you to use the full 4TB capacity for speed, while RAID 1 mirrors data for protection against drive failure. The Synology RX418 data does not list specific RAID configurations, as it is an expansion unit managed by a host NAS. Its features highlight online volume expansion and DSM management, implying RAID capabilities are handled by the primary system. For standalone RAID control, the Buffalo model provides clear options.
Compatibility
Operating system support determines which computers can access your files. The Buffalo LinkStation LS220 is compatible with Windows and macOS 15 (Sequoia) and earlier versions. It includes NAS Navigator 2 for macOS 15 and earlier, along with PC backup software. The Synology RX418 is managed via Synology DiskStation Manager (DSM), a platform known for broad compatibility with various operating systems, though specific OS versions are not listed in the provided data. The Buffalo unit offers clear, stated support for major desktop platforms out of the box.
Which NAS fits your needs
Users needing rackmount expansion
The Synology RX418 is a diskless 4-bay expansion unit designed for seamless storage upgrades. Its 12-inch depth allows it to fit in 2-post racks and wall mount racks. You manage it via Synology DiskStation Manager, enabling online volume expansion and energy-saving deep sleep mode. This makes it ideal for expanding existing setups without buying a new main NAS.
Home users wanting included drives
The Buffalo LinkStation 220 comes with 4TB of storage across two drive bays. It ships in RAID 1 for automatic backup, giving you 2TB of usable capacity. You can switch to RAID 0 for full 4TB. It includes NAS Navigator utility for automated backups and supports SSL encryption. This all-in-one package is ready for immediate use in home environments.
Buyers seeking plug-and-play security
This Buffalo unit features a closed system to reduce vulnerabilities from third-party apps. You get subscription-free personal cloud access for videos, music, and photos. The device allows individual folder access restrictions for secure sharing. It connects directly to your router for shared network storage on Windows and macOS. This setup centralizes your data without monthly fees.
Quick picks
| # | Product | Best for | Price |
|---|---|---|---|
| 1 | Synology 4-Bay Rackmount Expansion Unit | expanding Synology NAS storage capacity | Check price of Synology 4-Bay Rackmount Expansion Unit on Amazon |
| 2 | Buffalo LinkStation 220 4TB 2-Bay NAS | Home users needing secure, simple storage | Check price of Buffalo LinkStation 220 4TB 2-Bay NAS on Amazon |
The products compared
Synology 4-Bay Rackmount Expansion Unit
Best for: expanding Synology NAS storage capacity
- Number of Bays
- 4-Bay (what this guide is about)
- Drive Bays
- 4-Bay
- Included Storage
- Diskless
- Dimensions
- 17 × 11.4 × 1.73 inches
- Weight
- 9.44 pounds
View on Amazon: Synology 4-Bay Rackmount Expansion Unit Affiliate link
The Synology RX418 is a 4-bay expansion unit designed to add storage to existing Synology NAS systems. It arrives diskless, meaning you supply the drives. The unit measures 480 mm by 325 mm and weighs 9.44 pounds. It supports online volume expansion and deep sleep mode for energy savings. You manage it through Synology DiskStation Manager. This device fits 2-post racks and wall mounts.
Pros
- 4-bay capacity for drive expansion
- Plug-and-play design for seamless upgrades
- Supports online volume expansion
- Energy-saving deep sleep mode
Cons
- Sold diskless with no included storage
- Requires existing Synology NAS host system
- No internal drive trays included
Good fit if
- You need to expand storage on a Synology NAS
- You want to add four drives to your setup
- You prefer online volume expansion without downtime
Skip if
- You need a standalone NAS with built-in drives
- You use a non-Synology NAS system
- You want a device ready to use immediately
Verdict: Synology RX418 4-Bay Expansion Unit is a dedicated storage add-on for Synology users. It suits those who need more drive slots without buying a new main unit.
Buffalo LinkStation 220 4TB 2-Bay NAS
Best for: Home users needing secure, simple storage
- Number of Bays
- 2-Bay (what this guide is about)
- Drive Bays
- 2-Bay
- Included Storage
- 4TB
- RAID Support
- RAID 0, RAID 1
- Intended Use
- Home Users
- Dimensions
- 5.04 × 10 × 8.82 inches
View on Amazon: Buffalo LinkStation 220 4TB 2-Bay NAS Affiliate link
The Buffalo LinkStation 220 is a 2-bay NAS with 4TB of included storage. It supports RAID 0 for full capacity or RAID 1 for automatic backup. This closed system uses SSL encryption and excludes third-party apps to reduce vulnerabilities. It is intended for home users who want centralized storage and subscription-free personal cloud access on Windows and macOS 15 or earlier.
Pros
- Includes 4TB of storage across 2 drive bays
- Supports RAID 0 and RAID 1 configurations
- Closed system design reduces third-party app vulnerabilities
- SSL encryption for secure file transfers
- No monthly subscription fees for personal cloud access
Cons
- Limited to 4TB total capacity
- Only compatible with macOS 15 (Sequoia) and earlier
- Lacks support for macOS 26
Good fit if
- You need a simple, closed-system NAS for home use
- You want automatic data backup via RAID 1
- You use Windows or macOS 15 or earlier
Skip if
- You require macOS 26 compatibility
- You need more than 4TB of storage
- You want to install third-party apps
Verdict: Buffalo LinkStation 220 4TB 2-Bay NAS is a secure, entry-level storage solution for home users who prioritize data safety and simplicity over advanced features or newer macOS support.
Specifications side by side
| Spec | Synology 4-Bay Rackmount Expansion Unit | Buffalo LinkStation 220 4TB 2-Bay NAS |
|---|---|---|
| Drive Bays | 4-Bay | 2-Bay |
| Included Storage | Diskless | 4TB |
| RAID Support | not stated | RAID 0, RAID 1 |
| Number of Bays | 4-Bay | 2-Bay |
| Intended Use | not stated | Home Users |
| Dimensions | 17 × 11.4 × 1.73 inches | 5.04 × 10 × 8.82 inches |
| Weight | 9.44 pounds | 1 pounds |
| Size | 44 mm x 480 mm x 325 mm | 4TB (2x2TB) |
| Color | black | Black |
| Model | RX418 | LS220D0402 |
Frequently asked questions
Can I use a 4-bay NAS as a standalone device?
Yes, but only if it includes its own motherboard and controller. The Synology RX418 is a rackmount expansion unit, so it cannot operate alone. You must connect it to a main Synology NAS to function. It adds drive slots rather than acting as an independent server. A true standalone 4-bay NAS has all internal components integrated into one chassis.
Is a 2-bay NAS suitable for home backup?
Yes, the Buffalo LinkStation 220 is designed for home users needing simple, secure storage. It comes pre-loaded with 4TB of capacity using two 2TB drives. This setup provides immediate data safety without complex configuration. It prioritizes ease of use over advanced features, making it ideal for basic file backup and sharing in a household environment.
What is the size difference between these NAS types?
The physical dimensions vary significantly based on the model and bay count. The Synology RX418 measures 17 inches in length and 11.4 inches in width. It is a rackmount unit weighing 9.44 pounds. The Buffalo LinkStation 220 is smaller, measuring 10 inches wide and 8.82 inches high. It weighs only 1 pound, fitting easily on a desk.
Do I need to buy drives separately for a 4-bay NAS?
It depends on the specific model. The Synology RX418 is diskless, so you must purchase four drives separately to populate its bays. This allows you to choose drive capacities that fit your budget. In contrast, some 2-bay units like the Buffalo LinkStation 220 come with drives installed. Always check the product specifications to see if storage media is included.
Can a 4-bay expansion unit fit in a standard rack?
The Synology RX418 is designed for 2-post racks and wall mount racks. Its depth is 11.4 inches, which allows it to fit standard rack spaces. This form factor is distinct from desktop 4-bay NAS devices. If you need rackmount storage, this expansion unit integrates with your existing Synology system to increase capacity without replacing your main server.
Which NAS is better for simple home use?
The Buffalo LinkStation 220 is better for simple home use. It targets users who prioritize data safety and simplicity over advanced features. It offers a straightforward setup with pre-installed drives. The Synology RX418 requires a main NAS and technical knowledge to expand storage. For basic file storage and backup without complexity, the 2-bay Buffalo unit is the practical choice.