Synology 6 bay 2.5" NAS DS620slim (Diskless)
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AI Verdict
This 6-bay 2.5" NAS with 220 MB/s read is for users prioritizing a compact, quiet footprint and SSD performance over raw capacity or 10GbE speeds.
This NAS is a situational fit because its 2.5-inch drive bays and compact size directly address specific needs for quietness and small footprint. However, the 1GbE networking and dual-core CPU limit its utility for high-throughput or compute-intensive tasks, making it less suitable as a primary, high-performance server.
If you need faster network speeds, look for a NAS with at least 2.5GbE or 10GbE ports, or PCIe slots for network card upgrades.
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Pros
- Accommodates six 2.5-inch drives, allowing for all-SSD configurations for silent operation.
- Offers 220 MB/s reading and 190 MB/s writing speeds, even with encrypted data transmission.
- Supports 4K H.265/H.264 video transcoding on the fly for media streaming.
- Memory is expandable from 2GB DDR3L up to 6GB, which helps with multiple services.
- Features a compact physical size (121 x 151 x 175 mm) for placement in limited spaces.
- Includes dual 1GbE LAN ports with Link Aggregation for network redundancy or marginal throughput improvement.
Cons
- Network bottlenecked by dual 1GbE ports, preventing full utilization of SSD speeds.
- 2.5-inch drives are more expensive per TB and offer lower maximum capacities compared to 3.5-inch drives.
- Intel Celeron J3355 dual-core CPU can struggle with multiple virtual machines or heavy Docker workloads.
- Stock fan can be audible, with some users replacing it for quieter operation.
- Official RAM expansion limit of 6GB is restrictive for advanced use cases like multiple VMs.
Dimension Scores
The stated 220 MB/s read and 190 MB/s write are solid for a NAS, but the 1GbE ports limit real-world sustained transfers to around 113 MB/s.
Users consistently report the unit as reliable over several years, especially when configured with SSDs and proper RAID.
With a maximum raw capacity of 30 TB using 2.5-inch drives, it's average for a 6-bay unit but limited compared to 3.5-inch NAS options.
It supports 2.5-inch SATA HDDs and SSDs, various RAID types (SHR, RAID 0, 1, 5, 6, 10), and the extensive Synology DSM ecosystem.
Best For
- Home users needing a quiet, small-footprint media server with 4K transcoding capabilities.
- Small offices requiring a compact file server for document synchronization and backup.
- Users wanting an all-SSD NAS for low power consumption and silent operation.
- Environments with limited physical space where a traditional 3.5-inch NAS is too large.
Not Recommended For
- Power users needing 10GbE networking for extremely fast data transfers.
- Users requiring large, cost-effective storage volumes (e.g., 50TB+) due to 2.5-inch drive limitations.
- Running numerous demanding virtual machines or heavy containerized applications simultaneously.
Watch Out For
- The 1GbE network interface caps real-world transfer speeds, even with SSDs, to around 113 MB/s after overheads.
- The Intel Celeron J3355 CPU, while adequate for basic tasks, becomes a bottleneck for resource-intensive applications like multiple VMs, requiring significant RAM allocation.
- While the official RAM limit is 6GB, users report success with 8GB or even 16GB, but this is unsupported and may lead to instability.
- The cost per terabyte for 2.5-inch drives, especially SSDs, is significantly higher than for 3.5-inch drives, increasing the total investment for storage.
- The stock fan can produce noticeable noise, leading some users to replace it with aftermarket ultra-low noise fans for true silent operation.
Full Specifications
| ASIN | B07V6CC4M2 |
| Size | 6-bay; 2GB DDR3L |
| Brand | Synology |
| Color | white |
| Series | DS620slim |
| Material | Metal |
| Hard Drive | 30 TB |
| Item Weight | 3.08 pounds |
| Manufacturer | Synology |
| Item model number | DS620slim |
| Product Dimensions | 6.89 x 5.94 x 4.76 inches |
| Item Dimensions LxWxH | 6.89 x 5.94 x 4.76 inches |
| Is Discontinued By Manufacturer | No |
What Buyers Say
What really stands out is how many users swap out the stock fan for a Noctua, which tells you the original isn't cutting it for true silence. People love the tiny size and the ability to run all SSDs, making it super quiet and low power. But everyone mentions the 1GbE ports as a big miss, especially when you're loading it up with fast SSDs. The CPU is fine for basic stuff and 4K transcoding, but don't expect to run a bunch of heavy VMs without hitting a wall. It's a niche product, but for that niche, it works.
“Look, if you need something tiny and silent for your movies and photos, and you're okay with paying more for SSDs and not having crazy fast network speeds, this thing is actually pretty sweet. But seriously, that 1GbE is a joke with SSDs, Synology!”
Common Praise
- Extremely compact footprint, fitting into small spaces without issue.
- Very quiet operation, especially when populated with SSDs or after a fan replacement.
- Low power consumption, making it efficient for always-on operation.
- Handles 4K video transcoding for media streaming without significant issues.
- Synology's DSM software is feature-rich and user-friendly for file management and backups.
Common Complaints
- The 1GbE network interface bottlenecks potential SSD speeds.
- 2.5-inch drives are more expensive per TB and offer less capacity than 3.5-inch drives.
- The Intel Celeron J3355 CPU can be underpowered for demanding applications like multiple VMs.
- Stock fan noise is a recurring issue for users seeking absolute silence.
- Official RAM limit of 6GB is seen as insufficient by some for advanced use cases.
Ownership Tips
- The physical drive trays have locks, but they're more for preventing accidental removal than security.
- Upgrading the RAM unofficially to 8GB or 16GB is a common practice among users, despite Synology's 6GB limit.
- Many users replace the stock fan with a Noctua FN-A8 ULN for significantly quieter operation, which fits with minor adjustments.
- The unit runs cool even with SSDs, and the power consumption is minimal, making it ideal for continuous operation.
- While it has 6 bays, using two for SSD cache can feel wasteful if you need maximum raw storage capacity.
Frequently Asked Questions
Can I upgrade the RAM beyond the stated 6GB?
Officially, the system supports up to 6GB (2GB pre-installed + 4GB module). However, some users on Reddit have reported successfully installing 8GB or even 16GB, though this is not officially supported by Synology.
Does it support 3.5-inch hard drives?
No, the DS620slim is designed exclusively for 2.5-inch SATA HDDs and SSDs. Its compact physical dimensions prevent the installation of larger 3.5-inch drives.
Is the 1GbE network a bottleneck for SSDs?
Yes, the dual 1GbE ports (even with Link Aggregation) will limit the maximum transfer speeds to around 113 MB/s, which is below the potential of modern SSDs.
Can I use an SSD for caching to improve performance?
Yes, you can dedicate one or two bays for SSD caching. This can improve random read/write performance by accelerating frequently accessed data, but it won't increase sequential transfer speeds beyond the 1GbE limit.
Is it suitable for running a Plex Media Server with 4K transcoding?
The DS620slim supports dual-channel H.265/H.264 4K video transcoding on the fly. It can handle a couple of simultaneous 4K streams, but performance may be impacted by other active tasks on the NAS.
Buying Guide
When buying a NAS like this, you're essentially getting a mini-computer designed for storage. You'll need to buy the 2.5-inch drives separately, and your choice of SSDs or HDDs will impact cost, speed, and noise. Think about what you'll actually *do* with it: just storing files, streaming movies, or running apps? That dictates how much CPU and RAM you need, and whether the 1GbE network will be a bottleneck for your usage. Don't overspend on fast drives if your network can't keep up.
Drive Bays (6 x 2.5")
This tells you how many drives you can put in and their size. Six 2.5-inch bays means you can use smaller, quieter SSDs or laptop-sized HDDs, but they're more expensive per terabyte and offer less total capacity than larger 3.5-inch drives. More bays also mean more RAID flexibility for data protection.
Read/Write Speed (220 MB/s read, 190 MB/s write)
These numbers show how fast the NAS can theoretically move data. However, your actual speed will often be limited by your network connection. With 1GbE ports, you'll typically see speeds closer to 113 MB/s, so don't expect the full 220 MB/s unless you have a faster network connection.
Memory (2GB DDR3L, expandable to 6GB)
RAM is like the NAS's short-term memory. More RAM means it can handle more tasks simultaneously and run applications like Docker containers or virtual machines more smoothly. 2GB is fine for basic file serving, but 6GB is better for media streaming and light apps.
4K Video Transcoding
If you plan to stream high-resolution videos to devices that don't natively support the video format, the NAS needs to convert it on the fly (transcode). This feature means it has dedicated hardware to do that efficiently without bogging down the main CPU.
Alternatives
If you need more raw storage capacity and don't mind a larger footprint or some noise, look for NAS units with 3.5-inch drive bays. For higher network performance, search for models with 2.5GbE, 5GbE, or 10GbE ports, or those that support PCIe expansion cards for network upgrades.
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