Expand the network storage capacity for your small- to medium-business or SOHO (Small Office, Home Office) environment with the DiskStation DS1821+ 8-Bay NAS Enclosure from Synology. Useful for high-speed file sharing, backups, and surveillance, this enclosure supports up to eight 3.5" and 2.5" SATA drives in RAID 0, 1, 5, 6, 10, Synology Hybrid, and JBOD modes for up to 110,000 4K random read IOPS and 2300 MB/s sequential write speeds to handle demanding workloads. Installing up to two M.2 NVMe PCIe solid-state cache drives into the available slots can boost hard drive array performance by over 20x. In addition to having four Gigabit Ethernet ports with Link Aggregation and Failover support, the PCIe 3.0 x8 slot allows you to install expansion cards such as 10GbE network adapters to further enhance performance. The DiskStation DS1821+ works with Windows 7 and macOS 10.12 or later systems, and its integrated Synology DSM operating system supports a host of applications for file management, security, and more.
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Key Features
- 8 x 3.5" / 2.5" SATA Drive Bays
- 2 x M.2 2280 NVMe SSD Slots
- 2.2 GHz AMD Ryzen V1500B Quad-Core CPU
- 4GB DDR4 ECC RAM
Expand the network storage capacity for your small- to medium-business or SOHO (Small Office, Home Office) environment with the DiskStation DS1821+ 8-Bay NAS Enclosure from Synology. Useful for high-speed file sharing, backups, and surveillance, this enclosure supports up to eight 3.5" and 2.5" SATA drives in RAID 0, 1, 5, 6, 10, Synology Hybrid, and JBOD modes for up to 110,000 4K random read IOPS and 2300 MB/s sequential write speeds to handle demanding workloads. Installing up to two M.2 NVMe PCIe solid-state cache drives into the available slots can boost hard drive array performance by over 20x. In addition to having four Gigabit Ethernet ports with Link Aggregation and Failover support, the PCIe 3.0 x8 slot allows you to install expansion cards such as 10GbE network adapters to further enhance performance. The DiskStation DS1821+ works with Windows 7 and macOS 10.12 or later systems, and its integrated Synology DSM operating system supports a host of applications for file management, security, and more.
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Synology DS1821+ External HDD/SSD Overview
High-Performance NAS
The Synology DiskStation DS1821+ NAS enclosure is powered by a 2.2 GHz AMD Ryzen quad-core processor with 4GB of ECC DDR4 memory. It supports up to eight 3.5" and 2.5" SATA drives in RAID 0, 1, 5, 6, 10, Synology Hybrid, and JBOD modes with a maximum single volume size of 108TB.
Cache Acceleration
Installing up to two M.2 NVMe PCIe solid-state cache drives can accelerate hard drive array performance by over 20x.
Connectivity
The Synology DiskStation DS1821+ includes four Gigabit Ethernet ports with Link Aggregation and Failover support. Four USB 3.1 Gen 1 ports and two eSATA ports are available for connecting external storage drives and other devices to share across the network.
Scalability
A PCIe 3.0 slot is available for expansions such as 10GbE network adapters for high-speed data transfers and backups. Connecting up to two Synology DX517 5-bay expansion units to the DiskStation DS1821+ provides you with a total of 18 drive bays. Up to 32GB of memory can be installed across two SO-DIMM slots to further boost NAS performance and efficiency.
File Management and Sharing
The web-based File Station tool is built with intuitive, drag-and-drop operations for fast and secure file management from Windows and Mac computers. Advanced search and filtering tools allow for easy organization and file sharing, and the DS1821+ supports AFP, FTP, iSCSI, NFS, SMB, and WebDAV protocols.
Certified Storage Virtualization
Synology iSCSI storage supports most virtualization solutions to enhance work efficiency. Support includes VMware vSphere 6 and VAAI integration to help offload storage operations and optimize computation efficiency. Additionally, Windows Offloaded Data Transfer (ODX) speeds up data transfer and migration rate and OpenStack Cinder support turns your Synology NAS into a block-based storage component.
Versatile Backup Solutions
The Synology DiskStation DS1821+ integrates a variety of backup applications to fit your needs, including Active Backup for Business, Hyper Backup, Synology Drive, and Active Backup for Microsoft 365 / G Suite.
Synology DSM Applications
UPC: 846504003976
Synology DS1821+ External HDD/SSD Specs
Key Specs
| RAID | |
| Number of Bays | |
| Inputs/Outputs |
Computing
| CPU | |
| Processor | |
| Memory | |
| RAM Configuration / Capacity |
Drives
| RAID |
General
| Number of Bays | |
| Maximum Capacity | |
| Inputs/Outputs | |
| Media Card Slots | |
| PCI Expansion |
Networking
| Link Aggregation and Failover Support | |
| iSCSI Support |
Software
| Installed Operating System | |
| OS Compatibility | |
| Mobile App Compatible |
Security
| Encryption | |
| Security Features | |
| VPN Connections |
Electrical
| Input Power | |
| Power Consumption | |
| PSU |
Physical
| Operating Conditions | |
| Storage Conditions | |
| Certifications | |
| Cooling | |
| Noise Level | |
| Dimensions | |
| Weight |
Packaging Info
| Package Weight | |
| Box Dimensions (LxWxH) |
Synology DS1821+ External HDD/SSD Reviews
Symbology is the best
By Anthony
Rated 5 out of 5
Date: 2025-04-21
My best friend told me to buy Synology since my drop balls crashed and I’m so glad I did because it’s very excellent hardware easy to set up and very user-friendly. If you’re looking for a raid system synololgy is the best.
Solid Performer
By James
Rated 5 out of 5
Date: 2024-12-22
The DS1821+ can handle just about any drive brand and model, unlike its newer cousins. I use one as a Plex media server and a second as backup. I added 10GbE NICs to both as 4X1GbE ports do not provide the bandwidth I want to experience - I don't use them at all. I added 2 450GB M.2 NVME SSDs to the mix for cache purposes and experience 100% cache hit rates. The Ryzen CPU doesn't have much oomph and transcoding suffers as a result. I use an N100 NUC to transcode. Plex does not transcode well when installed on the DS1821+ as it lacks the Intel Quick Sync capabilities. I've used Synology's devices for 13 years and have found that it is easy to perform all of the functions I want in a NAS device.
See any errors on this page?
Why would you need a M.2 2280 NVMe SSD Slot on a ...
Why would you need a M.2 2280 NVMe SSD Slot on a NAS? What are good use cases for this feature?
The M.2 2280 slot on the Synology DiskStation DS1821+ 8-Bay NAS Enclosure allows for the NAS to have a sizeable cache to store frequently accessed files. This cache allows for the unit to utilize a read/write buffer to greatly increase the performance of the system.
Date published: 2024-10-02
Hi there, about the Ram Memory, i could use a OWC ...
Hi there, about the Ram Memory, i could use a OWC 16gb ddr4 2666 or just the synology memory?
I upgraded to 64GB RAM from a good RAM shop which would advise you for the type, but it uses about 3% of it. Unless you use RAM virtual machines, a better strategy is to use it for a while, see what you need, and THEN upgrade the RAM.
Date published: 2024-07-25
Does this have Hardware Encryption engine? Also ...
Does this have Hardware Encryption engine? Also will the Plex will work comfortably when streaming?
Streaming or transcoding. 2 different things. If you are doing direct play (your tv/device can decode the data stream without any help) it will work great. If you are transcoding video and/or audio (your tv doesnt support the type of video you have and it needs to re/encode it to another format) you will be limited to just a few streams and you will likely see your CPU utilization be very very high (plex has issues with atmos etc transcoding to other things). I have run plex for many many years and switched to emby recently. Its not as polished but it is fast and doesnt rely on being connected to the internet/plex servers to stream your local content.
Date published: 2024-06-18
Since it is now November of 2023, this is a ...
Since it is now November of 2023, this is a followup question to the compatibility of the Seagate 20TB Ironwulf drives. Support?
Synology does not list any 20TB drives on the compatibility list for the Synology DiskStation DS1821+ 8-Bay NAS Enclosure. The 16TB IronWolf Pro, B&H # SEST16000NT1, is the highest capacity IronWolf drive on Synology's compatibility list.
Date published: 2023-11-29
Can this be expanded by adding drives with an ...
Can this be expanded by adding drives with an active volume set up? Such as adding a 6th drive if you have 5 slots filled and already set up a running volume...
You can, and it will let you use the new drive to increase the size of an active volume.
There is a limit of 108TB/volume, so if you go over that, you will have to set up a second volume.
Date published: 2024-07-25
when i buy this do i just add my hdd's to have it ...
when i buy this do i just add my hdd's to have it working on my network as a nas or do i have to buy extra stuff?
The Synology DiskStation DS1821+ 8-Bay NAS Enclosure comes with Ethernet cables for you to set it up, and you just need the proper hard drive to start (it is recommended to use NAS-rated drives). You can also upgrade it with two M.2 (2280) drives and/or utilize the enclosure's PCIe 3.0 (x8) expansion slot, but it's not mandatory.
Date published: 2024-06-20
Is there any drive redundancy for if one hdd ...
Is there any drive redundancy for if one hdd fails?
The Synology DiskStation DS1821+ 8-Bay NAS Enclosure supports RAID 1 and 5 for instances of single drive failure, while RAID 6 would continue running with up to two drive failures.
Date published: 2024-06-20
What voltage is supported by the device?
What voltage is supported by the device?
It does both but i think you have to flip a switch on the power supply. Make sure you check to see if there is before you plug it in.
Date published: 2024-06-18