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Status: Legacy / discontinued
A 6-bay NAS with a 4-core Intel Xeon D-1527 and 8GB of ECC memory (error-correcting, up to 32GB). Two M.2 NVMe slots add SSD caching, there's a PCIe slot for upgrades, and two DX517 units take it to 16 drives. It ships with only two 1GbE ports, and it carries a 5-year warranty.
| Series | x21 Series |
|---|---|
| Bays | 6 |
| CPU | Intel Xeon D-1527 |
| Cores / Threads | 4 / 8 |
| RAM | 8 GB |
| CPU architecture | x86_64 |
| Support tier | full |
| Warranty (years) | 5 |
| Release year | 2020 |
| RAID levels | JBOD, RAID 0, RAID 1, RAID 5, RAID 6, RAID 10, RAID F1, SHR |
| PCIe slot types | 1x PCIe Gen 3 x8 |
| RAM (max) | 32 GB |
| Memory slots | 2 |
| Memory generation | DDR4 |
| Memory speed (MT/s) | 2666 MT/s |
| ECC memory | Supported |
| Memory module type | SODIMM |
| Replaceable memory | Replaceable |
| Network ports | 1x 10GbE + 2x 1GbE |
| USB ports | 3x USB 3.2 |
| PCIe expansion | 1 |
| M.2 slots | 2 |
| Max raw capacity | 96 |
| Drive bay types | 3.5" SATA HDD, 2.5" SATA SSD |
| Hot-swappable bays | Yes |
| CPU frequency (GHz) | 2.2 |
| Power supply (W) | 250 |
| Estimated cost to fill every bay with a certified 8 TB drive | about $2,430 new (Synology HAT3310-8T) / about $1,680 refurbished (Toshiba MG06ACA800E) / about $1,200 used (Synology HAT5310-8T) -- one observed eBay unit price incl. shipping x bays; quantity availability unverified |
| Estimated cost to fill every bay with a certified 16 TB drive | about $3,890 new (Seagate ST16000NE000) / about $2,550 refurbished (Seagate ST16000NM001G) / about $1,854 used (Seagate ST16000NM001G) -- one observed eBay unit price incl. shipping x bays; quantity availability unverified |
1 eBay listings checked Nov 9, 2026 · 1 new, 0 used (too few new listings to show a reliable new price)
Documents
Compatible network and expansion cards
Check the required OS, firmware, slot, bracket, and installation notes before buying.
| Component | Specifications | Evidence | Requirements and notes | Buy |
|---|---|---|---|---|
| Emulex OneConnect OCe11102-FM | Connector: LC Connector; Host interface: PCIe 2.0 x8; Ports: 2 x 10GbE | Officially certified Checked 2026-09-16 | Tested in 10GbE standard, FCoE\iSCSI hardware acceleration is not supported. | Amazon |
| Intel Ethernet Converged Network Adapter X520-SR2 | Connector: LC Connector; Host interface: PCIe 2.0 x8; Ports: 2 x 10GbE | Officially certified Checked 2026-09-16 | Intel Ethernet Converged Network Adapters (X520/X540) from Dell is not supported. | Search Amazon eBay |
| Intel Ethernet Converged Network Adapter X710-DA4 | Connector: SFP+; Host interface: PCIe 3.0 x8; Ports: 4 x 10GbE | Officially certified Checked 2026-09-16 | Firmware: 6.01. DSM version requirement: 6.2.1-23824 or later version. (Only applicable to models with DSM.) | Amazon eBay |
| Intel Ethernet Converged Network Adapter X710-T4 | Connector: RJ45; Host interface: PCIe 3.0 x8; Ports: 4 x 10GbE | Officially certified Checked 2026-09-16 | Firmware: 5.05. DSM version requirement: 6.2-23739 or later version. (Only applicable to models with DSM.) | Amazon eBay |
| Intel Ethernet Server Adapter I350-T4 | Connector: RJ45; Host interface: PCIe 2.0 x4; Ports: 4 x 1GbE | Officially certified Checked 2026-09-16 | Intel Ethernet Server Adapter (I350-T4) from Dell is not supported. | Amazon eBay |
| Intel Gigabit ET Dual Port Server Adapter | Connector: RJ45; Host interface: PCIe 2.0 x4; Ports: 2 x 1GbE | Officially certified Checked 2026-09-16 | See official installation instructions | Amazon eBay |
| Intel Gigabit ET2 Quad Port Server Adapter | Connector: RJ45; Host interface: PCIe 2.0 x4; Ports: 4 x 1GbE | Officially certified Checked 2026-09-16 | See official installation instructions | Amazon eBay |
| Mellanox ConnectX-3 Pro EN MCX312B-XCCT | Connector: SFP+; Host interface: PCIe 3.0 x8; Ports: 2 x 10GbE | Officially certified Checked 2026-09-16 | Firmware: 2.33.5100. DSM version requirement: 5.2-5644 or later version. (Only applicable to models with DSM.) | Amazon eBay |
| Mellanox ConnectX-4 Lx EN MCX4121A-XCAT | Connector: SFP28; Host interface: PCIe 3.0 x8; Ports: 2 x 10GbE | Officially certified Checked 2026-09-16 | Firmware: 14.20.1010. DSM version requirement: 6.2-23739 or later version. (Only applicable to models with DSM.); For better performance, we strongly recommend installing the network interface card into the PCIe 3.0 x8 (white) slot first. (Only applicable to RS3617xs, RS3614xs+, RS3614xs, and RS3614RPxs) | Amazon eBay |
| Synology E10G30-F2 | Connector: SFP+; Host interface: PCIe 3.0 x8; Ports: 2 x 10GbE | Officially certified Checked 2026-09-16 | DSM version requirement: 7.1.1-42962 Update 5 or later version. (Only applicable to models with DSM.); DSM Enterprise version requirement: 1.0-101178 or later version. (Only applicable to models with DSM Enterprise.); Remote Direct Memory Access (RDMA): Available on PAS7700 only. Applies to NFS over RDMA and NVMe over RDMA. | Amazon eBay |
| Synology E10G30-T2 | Connector: RJ45; Host interface: PCIe 3.0 x8; Ports: 2 x 10GbE | Officially certified Checked 2026-09-16 | APM version requirement: 1.0-71430 or later version. (Only applicable to models with APM.); DSM version requirement: 7.1.1-42962 Update 5 or later version. (Only applicable to models with DSM.); DSM Enterprise version requirement: 1.0-101178 or later version. (Only applicable to models with DSM Enterprise.); Remote Direct Memory Access (RDMA): Available on PAS7700 only. Applies to NFS over RDMA and NVMe over RDMA. | Amazon eBay |
| Synology E25G30-F2 | Connector: SFP28; Host interface: PCIe 3.0 x8; Ports: 2 x 25GbE | Officially certified Checked 2026-09-16 | APM version requirement: 1.0-71430 or later version. (Only applicable to models with APM.); DSM version requirement: 7.1.1-42962 Update 5 or later version. (Only applicable to models with DSM.); DSM Enterprise version requirement: 1.0-101178 or later version. (Only applicable to models with DSM Enterprise.); Remote Direct Memory Access (RDMA): Available on PAS7700 only. Applies to NFS over RDMA and NVMe over RDMA.; For models with an AMD Ryzen V1000 CPU, DSM version 7.2.1-69057 or above is required. | Amazon eBay |
| Synology E10G17-F2 (EOL) | Connector: SFP+; Host interface: PCIe 3.0 x8; Ports: 2 x 10GbE | Officially certified Checked 2026-09-16 | DSM version requirement: 6.0.2-8451 or later version. (Only applicable to models with DSM.) | Amazon eBay |
| Synology E10G18-T1 (EOL) | Connector: RJ45; Host interface: PCIe 3.0 x4; Ports: 1 x 10GbE | Officially certified Checked 2026-09-16 | DSM version requirement: 6.2-23739-2 onward (or 6.1-15284-2 onward with DSM 6.1). (Only applicable to models with DSM.) | Amazon eBay |
| Synology E10G18-T2 (EOL) | Connector: RJ45; Host interface: PCIe 3.0 x8; Ports: 2 x 10GbE | Officially certified Checked 2026-09-16 | DSM version requirement: 6.2.1-23824 or later version. (Only applicable to models with DSM.) | Amazon eBay |
| Synology E10G21-F2 (EOL) | Connector: SFP+; Host interface: PCIe 3.0 x8; Ports: 2 x 10GbE | Officially certified Checked 2026-09-16 | DSM version requirement: 6.2.3-25426 or later version. (Only applicable to models with DSM.) | Amazon eBay |
| Synology E25G21-F2 (EOL) | Connector: SFP28; Host interface: PCIe 3.0 x8; Ports: 2 x 25GbE | Officially certified Checked 2026-09-16 | DSM version requirement: 6.2.3-25426 or later version. (Only applicable to models with DSM.); For best performance, we recommend using memory in dual-channel configuration. For instructions, refer to Hardware Installation Guide. | Amazon |
Compatible Drives
101 drives certified on DS1621xs+'s official manufacturer compatibility list, sourced directly from Synology's own published Hardware Compatibility List. Each model links to that drive's own compatibility page.
101certified models
5drive brands
24 TBlargest listed
99with verified extra specs
Certified drives by capacity
0.48 TB4
0.96 TB4
1 TB4
1.92 TB4
2 TB10
3 TB1
3.84 TB4
4 TB8
6 TB6
7 TB1
8 TB16
10 TB11
12 TB12
14 TB5
16 TB6
18 TB1
20 TB3
24 TB1
Show all 101 certified drives
101 shown
| Brand | Model | Capacity | Type | Verified drive details | Recently observed offers | Status | Firmware |
|---|---|---|---|---|---|---|---|
| Synology | HAT5320-24T details | 24.0 TB | 3.5" NAS HDD | 7200 RPM · 1024 MB cache · CMR · 550 TB/year workload · 2500000 h MTBF · 5-year warranty | New: $1,553.83 | Recommended | 1401 |
| Synology | HAT5310-20T details | 20.0 TB | 3.5" Enterprise HDD | 7200 RPM · 512 MB cache · CMR · 550 TB/year workload · 2500000 h MTBF · 5-year warranty | New: $899.95 · Used: $1,440.13 | Recommended | 1401 |
| Synology | HAT3320-20T details | 20.0 TB | 3.5" NAS HDD | 7200 RPM · 1024 MB cache · CMR · 180 TB/year workload · 1200000 h MTBF · 3-year warranty | New: $806.19 · Used: $780.00 | Recommended | 1401 |
| Synology | HAT5320-20T details | 20.0 TB | 3.5" NAS HDD | 7200 RPM · 1024 MB cache · CMR · 550 TB/year workload · 2500000 h MTBF · 5-year warranty | New: $1,419.79 | Recommended | 1402 |
| Synology | HAT5310-18T details | 18.0 TB | 3.5" Enterprise HDD | 7200 RPM · 512 MB cache · CMR · 550 TB/year workload · 2500000 h MTBF · 5-year warranty | No recent verified offer | Recommended | 1401 |
| Synology | HAT5300-16T details | 16.0 TB | 3.5" Enterprise HDD | 7200 RPM · 512 MB cache · CMR · 550 TB/year workload · 2500000 h MTBF · 5-year warranty | New: $782.49 · Used: $399.00 | Recommended | 1402 |
| Seagate | ST16000NM001G details | 16.0 TB | 3.5" Enterprise HDD | 7200 RPM · 256 MB cache · CMR · 550 TB/year workload · 2500000 h MTBF · 5-year warranty | New: $349.00 · Refurb: $424.99 | Recommended | SN02 |
| Synology | HAT5310-16T details | 16.0 TB | 3.5" Enterprise HDD | 7200 RPM · 512 MB cache · CMR · 550 TB/year workload · 2500000 h MTBF · 5-year warranty | New: $1,064.99 | Recommended | 1403 |
| Seagate | ST16000NE000 details | 16.0 TB | 3.5" NAS HDD | 7200 RPM · 256 MB cache · CMR · 300 TB/year workload · 1200000 h MTBF · 5-year warranty | New: $648.25 · Used: $489.00 | Recommended | EN02 |
| Toshiba | MG08ACA16TE details | 16.0 TB | 3.5" Enterprise HDD | 7200 RPM · 512 MB cache · CMR · 550 TB/year workload · 2500000 h MTBF · 5-year warranty | New: $1,199.10 · Refurb: $599.00 | Recommended | 0101 |
| Synology | HAT3310-16T details | 16.0 TB | 3.5" NAS HDD | 7200 RPM · 512 MB cache · CMR · 180 TB/year workload · 1200000 h MTBF · 3-year warranty | New: $693.99 · Used: $505.00 | Recommended | 1402 |
| Seagate | ST14000NE0008 details | 14.0 TB | 3.5" NAS HDD | 7200 RPM · 256 MB cache · CMR · 300 TB/year workload · 1200000 h MTBF · 5-year warranty | New: $423.65 | Recommended | EN01 |
| Seagate | ST14000NM0018 details | 14.0 TB | 3.5" Enterprise HDD | 7200 RPM · 256 MB cache · CMR · 2500000 h MTBF · 5-year warranty | New: $470.00 | Recommended | SN02 |
| Toshiba | MG07ACA14TE details | 14.0 TB | 3.5" Enterprise HDD | 7200 RPM · 256 MB cache · CMR · 550 TB/year workload · 2500000 h MTBF · 3-year warranty | Refurb: $661.78 · Used: $399.00 | Recommended | 0101 |
| Western Digital | WUH721414ALE6L4 details | 14.0 TB | 3.5" Enterprise HDD | 7200 RPM · 512 MB cache · CMR · 550 TB/year workload · 2500000 h MTBF · 5-year warranty | Used: $388.00 | Recommended | LDGNW240 |
| Seagate | ST14000NM001G details | 14.0 TB | 3.5" Enterprise HDD | 7200 RPM · 256 MB cache · CMR · 550 TB/year workload · 2500000 h MTBF · 5-year warranty | New: $410.00 · Used: $325.00 | Recommended | SN02 |
| HGST | HUH721212ALE604 details | 12.0 TB | 3.5" Enterprise HDD | 7200 RPM · 256 MB cache · CMR · 550 TB/year workload · 2500000 h MTBF · 5-year warranty | No recent verified offer | Recommended | - |
| HGST | HUH721212ALE600 details | 12.0 TB | 3.5" Enterprise HDD | 7200 RPM · 256 MB cache · CMR · 550 TB/year workload · 2500000 h MTBF · 5-year warranty | New: $330.00 · Used: $244.99 | Recommended | LEGNT3D0 |
| Seagate | ST12000NM0008 details | 12.0 TB | 3.5" Enterprise HDD | 7200 RPM · 256 MB cache · CMR · 550 TB/year workload · 2500000 h MTBF · 5-year warranty | New: $450.00 · Used: $259.99 | Recommended | SN02 |
| Seagate | ST12000NM001G details | 12.0 TB | 3.5" Enterprise HDD | 7200 RPM · 256 MB cache · CMR · 550 TB/year workload · 2500000 h MTBF · 5-year warranty | New: $442.00 · Used: $374.99 | Recommended | SN02 |
| Synology | HAT5300-12T details | 12.0 TB | 3.5" Enterprise HDD | 7200 RPM · 256 MB cache · CMR · 550 TB/year workload · 2500000 h MTBF · 5-year warranty | New: $589.99 · Used: $379.99 | Recommended | 1401 |
| Synology | HAT3300-12T details | 12.0 TB | 3.5" NAS HDD | 7200 RPM · 256 MB cache · CMR · 180 TB/year workload · 1000000 h MTBF · 3-year warranty | No recent verified offer | Recommended | PL01 |
| Seagate | ST12000NE0008 details | 12.0 TB | 3.5" NAS HDD | 7200 RPM · 256 MB cache · CMR · 300 TB/year workload · 1200000 h MTBF · 5-year warranty | New: $445.00 · Refurb: $384.99 | Recommended | - |
| Synology | HAT3310-12T details | 12.0 TB | 3.5" NAS HDD | 7200 RPM · 512 MB cache · CMR · 180 TB/year workload · 1200000 h MTBF · 3-year warranty | New: $550.99 | Recommended | 1402 |
| Western Digital | WD121KRYZ details | 12.0 TB | 3.5" Enterprise HDD | 7200 RPM · 256 MB cache · CMR · 219 TB/year workload · 2500000 h MTBF · 5-year warranty | Refurb: $349.99 | Recommended | - |
| Seagate | ST12000NE0007 details | 12.0 TB | 3.5" NAS HDD | 7200 RPM · 256 MB cache · CMR · 300 TB/year workload · 1200000 h MTBF · 5-year warranty | Used: $397.00 | Recommended | EN01 |
| Western Digital | WD121KFBX details | 12.0 TB | 3.5" NAS HDD | 7200 RPM · 256 MB cache · CMR · 550 TB/year workload · 2000000 h MTBF · 5-year warranty | Used: $425.00 | Recommended | 83.00A83 |
| Toshiba | MG07ACA12TE details | 12.0 TB | 3.5" Enterprise HDD | 7200 RPM · 256 MB cache · CMR · 550 TB/year workload · 2500000 h MTBF · 3-year warranty | Refurb: $501.32 · Used: $369.50 | Recommended | - |
| Seagate | ST10000NE0008 details | 10.0 TB | 3.5" NAS HDD | 7200 RPM · 256 MB cache · CMR · 300 TB/year workload · 1200000 h MTBF · 5-year warranty | New: $471.70 · Used: $257.29 | Recommended | EN02 |
| Seagate | ST10000NM0478 details | 10.0 TB | 3.5" Enterprise HDD | 7200 RPM · 256 MB cache · CMR · 2500000 h MTBF · 5-year warranty | New: $300.00 · Used: $444.27 | Recommended | SN02 |
| Seagate | ST10000NE0004 details | 10.0 TB | 3.5" NAS HDD | 7200 RPM · 256 MB cache · CMR · 300 TB/year workload · 1200000 h MTBF · 5-year warranty | New: $473.10 | Recommended | - |
| Western Digital | WD102KFBX details | 10.0 TB | 3.5" NAS HDD | 7200 RPM · 256 MB cache · CMR · 550 TB/year workload · 2000000 h MTBF · 5-year warranty | New: $500.00 · Used: $399.94 | Recommended | 83.00A83 |
| Seagate | ST10000NM0086 details | 10.0 TB | 3.5" Enterprise HDD | 7200 RPM · 256 MB cache · CMR · 550 TB/year workload · 2500000 h MTBF · 5-year warranty | New: $423.15 · Refurb: $275.00 | Recommended | SN05 |
| Western Digital | WUS721010ALE6L4 details | 10.0 TB | 3.5" Enterprise HDD | 7200 RPM · 256 MB cache · CMR · 550 TB/year workload · 2000000 h MTBF · 5-year warranty | New: $436.65 · Used: $398.98 | Recommended | VXGNW920 |
| HGST | HUH721010ALE600 details | 10.0 TB | 3.5" Enterprise HDD | 7200 RPM · 256 MB cache · CMR · 550 TB/year workload · 2500000 h MTBF · 5-year warranty | New: $321.00 · Refurb: $269.99 | Recommended | LHGNT384 |
| Western Digital | WD102KRYZ details | 10.0 TB | 3.5" Enterprise HDD | 7200 RPM · 256 MB cache · CMR · 550 TB/year workload · 2000000 h MTBF · 5-year warranty | Used: $306.19 | Recommended | 01.01H01 |
| Seagate | ST10000NM001G details | 10.0 TB | 3.5" Enterprise HDD | 7200 RPM · 256 MB cache · CMR · 550 TB/year workload · 2500000 h MTBF · 5-year warranty | New: $396.00 · Used: $299.99 | Recommended | SN02 |
| Western Digital | WD101KFBX details | 10.0 TB | 3.5" NAS HDD | 7200 RPM · 256 MB cache · CMR · 300 TB/year workload · 1000000 h MTBF · 5-year warranty | New: $475.00 · Used: $349.00 | Recommended | 83.H0A03 |
| Toshiba | MG06ACA10TE details | 10.0 TB | 3.5" Enterprise HDD | 7200 RPM · 256 MB cache · CMR · 550 TB/year workload · 2500000 h MTBF · 3-year warranty | New: $500.70 | Recommended | 0104 |
| HGST | HUH721008ALE600 details | 8.0 TB | 3.5" Enterprise HDD | 7200 RPM · 256 MB cache · CMR · 550 TB/year workload · 2500000 h MTBF · 5-year warranty | Used: $248.51 | Recommended | - |
| Seagate | ST8000NE0004 details | 8.0 TB | 3.5" NAS HDD | 7200 RPM · 256 MB cache · CMR · 300 TB/year workload · 1200000 h MTBF · 5-year warranty | New: $812.33 · Used: $492.75 | Recommended, EOL | EN02 |
| Synology | HAT3320-8T details | 8.0 TB | 3.5" NAS HDD | 7200 RPM · 512 MB cache · CMR · 300 TB/year workload · 1200000 h MTBF · 3-year warranty | New: $554.00 | Recommended | 1401 |
| Seagate | ST8000NE0008 details | 8.0 TB | 3.5" NAS HDD | 7200 RPM · CMR · 1200000 h MTBF · 5-year warranty | No recent verified offer | Recommended | - |
| Synology | HAT3310-8T details | 8.0 TB | 3.5" NAS HDD | 7200 RPM · 256 MB cache · CMR · 180 TB/year workload · 1200000 h MTBF · 3-year warranty | New: $405.00 · Used: $295.00 | Recommended | 1403 |
| Synology | HAT5310-8T details | 8.0 TB | 3.5" Enterprise HDD | 7200 RPM · 256 MB cache · CMR · 550 TB/year workload · 2500000 h MTBF · 5-year warranty | New: $1,027.37 · Used: $199.99 | Recommended | 1402 |
| Seagate | ST8000NM0206 details | 8.0 TB | 3.5" Enterprise HDD | 7200 RPM · 256 MB cache · CMR · 550 TB/year workload · 2500000 h MTBF · 5-year warranty | No recent verified offer | Recommended, EOL | SN05 |
| Synology | HAT5320-8T details | 8.0 TB | 3.5" Enterprise HDD | 7200 RPM · 512 MB cache · CMR · 550 TB/year workload · 2000000 h MTBF · 5-year warranty | New: $702.17 | Recommended | 1401 |
| Seagate | ST8000NM000A details | 8.0 TB | 3.5" Enterprise HDD | 7200 RPM · 256 MB cache · CMR · 550 TB/year workload · 2000000 h MTBF · 5-year warranty | New: $414.99 · Used: $249.00 | Recommended | SN02 |
| Synology | HAT3300-8T details | 8.0 TB | 3.5" NAS HDD | 5400 RPM · 256 MB cache · CMR · 180 TB/year workload · 1000000 h MTBF · 3-year warranty | Used: $299.99 | Recommended | PL01 |
| Seagate | ST8000NE001 details | 8.0 TB | 3.5" NAS HDD | 7200 RPM · 256 MB cache · CMR · 300 TB/year workload · 1200000 h MTBF · 5-year warranty | New: $408.35 · Refurb: $314.99 | Recommended | EN01 |
| Western Digital | WD8003FFBX details | 8.0 TB | 3.5" NAS HDD | 7200 RPM · 256 MB cache · CMR · 550 TB/year workload · 2000000 h MTBF · 5-year warranty | Used: $295.00 | Recommended | 83.00A83 |
| Toshiba | MG06ACA800E details | 8.0 TB | 3.5" Enterprise HDD | 7200 RPM · 256 MB cache · CMR · 550 TB/year workload · 2500000 h MTBF · 5-year warranty | New: $424.00 · Refurb: $279.99 | Recommended | - |
| Western Digital | HUS728T8TALE6L4 details | 8.0 TB | 3.5" Enterprise HDD | 7200 RPM · 256 MB cache · CMR · 550 TB/year workload · 2000000 h MTBF · 5-year warranty | New: $599.00 | Recommended | V8GNW460 |
| Synology | HAT5300-8T details | 8.0 TB | 3.5" Enterprise HDD | 7200 RPM · 256 MB cache · CMR · 550 TB/year workload · 2500000 h MTBF · 5-year warranty | New: $998.00 · Used: $225.00 | Recommended | 1401 |
| Western Digital | WD8004FRYZ details | 8.0 TB | 3.5" Enterprise HDD | 7200 RPM · 256 MB cache · CMR · 550 TB/year workload · 2000000 h MTBF · 5-year warranty | New: $399.99 · Used: $299.99 | Recommended | 01.01H01 |
| Synology | SAT5210-7000G details | 7.0 TB | 2.5" Enterprise SSD | 1500000 h MTBF · 5-year warranty · 10000 TBW | New: $7,439.58 | Recommended | SCEMH5.0 |
| Synology | HAT3300-6T details | 6.0 TB | 3.5" NAS HDD | 5400 RPM · 256 MB cache · CMR · 180 TB/year workload · 1000000 h MTBF · 3-year warranty | New: $306.99 · Used: $211.00 | Recommended | PL01 |
| Seagate | ST6000NE0023 details | 6.0 TB | 3.5" NAS HDD | 7200 RPM · 256 MB cache · CMR · 300 TB/year workload · 1200000 h MTBF · 5-year warranty | New: $289.00 · Used: $175.00 | Recommended | - |
| Toshiba | MG06ACA600E details | 6.0 TB | 3.5" Enterprise HDD | 7200 RPM · 256 MB cache · CMR · 550 TB/year workload · 2500000 h MTBF · 5-year warranty | New: $346.54 · Refurb: $220.00 | Recommended | - |
| Seagate | ST6000NE000 details | 6.0 TB | 3.5" NAS HDD | 7200 RPM · 256 MB cache · CMR · 300 TB/year workload · 1200000 h MTBF · 5-year warranty | New: $218.32 · Used: $199.12 | Recommended | EN01 |
| Western Digital | WD6003FFBX details | 6.0 TB | 3.5" NAS HDD | 7200 RPM · 256 MB cache · CMR · 550 TB/year workload · 2000000 h MTBF · 5-year warranty | New: $479.06 | Recommended | 83.00A83 |
| Seagate | ST6000NM021A details | 6.0 TB | 3.5" Enterprise HDD | 7200 RPM · 256 MB cache · CMR · 550 TB/year workload · 2000000 h MTBF · 5-year warranty | New: $200.67 · Refurb: $220.00 | Recommended | SN02 |
| Seagate | ST4000NE0025 details | 4.0 TB | 3.5" NAS HDD | 7200 RPM · 128 MB cache · CMR · 300 TB/year workload · 1200000 h MTBF · 5-year warranty | New: $163.17 · Used: $129.99 | Recommended | - |
| Western Digital | WD4003FFBX details | 4.0 TB | 3.5" NAS HDD | 7200 RPM · 256 MB cache · CMR · 550 TB/year workload · 2000000 h MTBF · 5-year warranty | New: $289.19 · Used: $104.93 | Recommended | - |
| Synology | HAT3300-4T details | 4.0 TB | 3.5" NAS HDD | 5400 RPM · 256 MB cache · CMR · 180 TB/year workload · 1000000 h MTBF · 3-year warranty | New: $348.72 · Used: $175.00 | Recommended | PL01 |
| Seagate | ST4000NE001 details | 4.0 TB | 3.5" NAS HDD | 7200 RPM · 256 MB cache · CMR · 300 TB/year workload · 1200000 h MTBF · 5-year warranty | New: $139.00 · Used: $127.50 | Recommended | EN01 |
| Synology | HAT5300-4T details | 4.0 TB | 3.5" Enterprise HDD | 7200 RPM · 256 MB cache · CMR · 550 TB/year workload · 2000000 h MTBF · 5-year warranty | No recent verified offer | Recommended | 1403 |
| Synology | HAT5320-4T details | 4.0 TB | 3.5" NAS HDD | 7200 RPM · 512 MB cache · CMR · 550 TB/year workload · 2000000 h MTBF · 5-year warranty | New: $567.27 | Recommended | 1401 |
| Seagate | ST4000NM002A details | 4.0 TB | 3.5" Enterprise HDD | 7200 RPM · 256 MB cache · CMR · 550 TB/year workload · 2000000 h MTBF · 5-year warranty | New: $134.99 · Used: $79.99 | Recommended | SN02 |
| Toshiba | MG04ACA400E details | 4.0 TB | 3.5" Enterprise HDD | 7200 RPM · 128 MB cache · CMR · 550 TB/year workload · 1400000 h MTBF · 5-year warranty | New: $270.76 · Refurb: $175.00 | Recommended | FP4B |
| Synology | SAT5220-3840G details | 3.84 TB | 2.5" Enterprise SSD | 1500000 h MTBF · 5-year warranty · 7000 TBW | No recent verified offer | Recommended | SCEMH5.0 |
| Synology | SAT5200-3840G details | 3.84 TB | 2.5" Enterprise SSD | 1500000 h MTBF · 5-year warranty · 9162 TBW | No recent verified offer | Recommended | SCEMJ2.1 |
| Synology | SAT5210-3840G details | 3.84 TB | 2.5" Enterprise SSD | 1500000 h MTBF · 5-year warranty · 8533 TBW | No recent verified offer | Recommended | SCEMH3.1 |
| Synology | SAT5221-3840G details | 3.84 TB | 2.5" Enterprise SSD | 1500000 h MTBF · 5-year warranty · 7000 TBW | New: $3,803.00 | Recommended | SCEM16.3 |
| Toshiba | MG04ACA300E details | 3.0 TB | 3.5" Enterprise HDD | 7200 RPM · 128 MB cache · CMR · 550 TB/year workload · 1400000 h MTBF · 5-year warranty | New: $284.00 · Used: $59.99 | Recommended | FP4B |
| Seagate | ST2000NX0253 details | 2.0 TB | 2.5" Enterprise HDD | 7200 RPM · 128 MB cache · CMR · 550 TB/year workload · 2000000 h MTBF · 5-year warranty | New: $99.99 · Refurb: $58.99 | Recommended | SN02 |
| HGST | HUS722T2TALA604 details | 2.0 TB | 3.5" Enterprise HDD | 7200 RPM · 128 MB cache · CMR · 2000000 h MTBF · 5-year warranty | New: $284.13 · Used: $114.99 | Recommended | RAGNWA07 |
| Western Digital | WD2005FBYZ details | 2.0 TB | 3.5" Enterprise HDD | 7200 RPM · 128 MB cache · CMR · 219 TB/year workload · 2000000 h MTBF · 5-year warranty | New: $87.55 · Used: $86.90 | Recommended | - |
| Western Digital | WD2002FFSX details | 2.0 TB | 3.5" NAS HDD | 7200 RPM · 64 MB cache · CMR · 550 TB/year workload · 2000000 h MTBF · 5-year warranty | New: $221.32 · Refurb: $411.18 | Recommended | 81.00A81 |
| Toshiba | MG04ACA200E details | 2.0 TB | 3.5" Enterprise HDD | 7200 RPM · 128 MB cache · CMR · 550 TB/year workload · 1400000 h MTBF · 5-year warranty | New: $186.08 · Refurb: $300.00 | Recommended | FP4B |
| Synology | HAT3300-2T details | 2.0 TB | 3.5" NAS HDD | 5400 RPM · 256 MB cache · CMR · 180 TB/year workload · 1000000 h MTBF · 3-year warranty | New: $671.92 · Used: $139.99 | Recommended | PL01 |
| Western Digital | WD2005VBYZ details | 2.0 TB | 3.5" Enterprise HDD | - | No recent verified offer | Recommended | - |
| Seagate | ST2000NE001 details | 2.0 TB | 3.5" NAS HDD | 7200 RPM · 256 MB cache · CMR · 300 TB/year workload · 1200000 h MTBF · 5-year warranty | New: $366.61 | Recommended, EOL | EN01 |
| Seagate | ST2000NE0025 details | 2.0 TB | 3.5" NAS HDD | 7200 RPM · 128 MB cache · CMR · 300 TB/year workload · 1200000 h MTBF · 5-year warranty | New: $93.40 · Used: $317.77 | Recommended | EN02 |
| Seagate | ST2000NM001A details | 2.0 TB | 3.5" Enterprise HDD | 7200 RPM · 256 MB cache · CMR · 550 TB/year workload · 2000000 h MTBF · 5-year warranty | Refurb: $270.76 · Used: $49.00 | Recommended | SN02 |
| Synology | SAT5210-1920G details | 1.92 TB | 2.5" Enterprise SSD | 1500000 h MTBF · 5-year warranty · 4800 TBW | No recent verified offer | Recommended | SCEMH3.2 |
| Synology | SAT5220-1920G details | 1.92 TB | 2.5" Enterprise SSD | 1500000 h MTBF · 5-year warranty · 3500 TBW | New: $799.99 | Recommended | SCEMH5.0 |
| Synology | SAT5221-1920G details | 1.92 TB | 2.5" Enterprise SSD | 1500000 h MTBF · 5-year warranty · 3500 TBW | New: $2,200.01 · Refurb: $2,255.63 | Recommended | SCEM16.3 |
| Synology | SAT5200-1920G details | 1.92 TB | 2.5" Enterprise SSD | 1500000 h MTBF · 5-year warranty · 4581 TBW | No recent verified offer | Recommended | SCEMJ2.1 |
| Seagate | ST1000NX0313 details | 1.0 TB | 2.5" Enterprise HDD | 7200 RPM · 128 MB cache · CMR · 550 TB/year workload · 2000000 h MTBF · 5-year warranty | New: $54.30 · Used: $24.99 | Recommended | - |
| Western Digital | WD1005FBYZ details | 1.0 TB | 3.5" Enterprise HDD | 7200 RPM · 128 MB cache · 219 TB/year workload · 2000000 h MTBF · 5-year warranty | New: $66.46 · Used: $124.99 | Recommended, EOL | - |
| HGST | HUS722T1TALA604 details | 1.0 TB | 3.5" Enterprise HDD | 7200 RPM · 128 MB cache · CMR · 550 TB/year workload · 2000000 h MTBF · 5-year warranty | New: $119.99 · Refurb: $200.57 | Recommended | - |
| Western Digital | WD1005VBYZ details | 1.0 TB | 3.5" Enterprise HDD | - | No recent verified offer | Recommended, EOL | - |
| Synology | SAT5200-960G details | 0.96 TB | 2.5" Enterprise SSD | 1500000 h MTBF · 5-year warranty · 2290 TBW | No recent verified offer | Recommended | SCEMJ2.1 |
| Synology | SAT5210-960G details | 0.96 TB | 2.5" Enterprise SSD | 1500000 h MTBF · 5-year warranty · 2194 TBW | No recent verified offer | Recommended | SCEMH3.2 |
| Synology | SAT5221-960G details | 0.96 TB | 2.5" Enterprise SSD | 1500000 h MTBF · 5-year warranty · 1700 TBW | New: $1,177.29 | Recommended | F3MN902 |
| Synology | SAT5220-960G details | 0.96 TB | 2.5" Enterprise SSD | 1500000 h MTBF · 5-year warranty · 1700 TBW | No recent verified offer | Recommended | SCEMH5.0 |
| Synology | SAT5210-480G details | 0.48 TB | 2.5" Enterprise SSD | 1500000 h MTBF · 5-year warranty · 1097 TBW | No recent verified offer | Recommended | SCEMH3.1 |
| Synology | SAT5220-480G details | 0.48 TB | 2.5" Enterprise SSD | 1500000 h MTBF · 5-year warranty · 900 TBW | No recent verified offer | Recommended | SCEMH5.0 |
| Synology | SAT5221-480G details | 0.48 TB | 2.5" Enterprise SSD | 1500000 h MTBF · 5-year warranty · 900 TBW | No recent verified offer | Recommended | F3MN902 |
| Synology | SAT5200-480G details | 0.48 TB | 2.5" Enterprise SSD | 1500000 h MTBF · 5-year warranty · 1145 TBW | No recent verified offer | Recommended | SCEMJ2.1 |
Extra drive details are published only from manufacturer-owned documents or explicit human review. Follow the model link for field-level sources.
Certified list last checked 2026-08-18.
Compatible Memory
3 memory modules listed by Synology as compatible with DS1621xs+. Third-party modules may also work, but are not shown here unless Synology itself lists them as compatible.
3certified modules
8–16 GBcapacity range
| SKU | Capacity | DDR generation | ECC | Form factor | Rated speed | Warranty | Source and notes | Buy |
|---|---|---|---|---|---|---|---|---|
| D4ECSO-2666-16G | 16 GB | DDR4 | ECC | SODIMM | 2666 MT/s | 5-year | Manufacturer source Checked 2026-09-16 | Amazon eBay |
| D4ES03-16G | 16 GB | DDR4 | ECC | SODIMM | - | 5-year | Manufacturer source Checked 2026-09-16 | Amazon eBay |
| D4ES01-8G | 8 GB | DDR4 | ECC | SODIMM | - | 5-year | Manufacturer source Checked 2026-09-16 | Amazon eBay |
Certified list last checked 2026-09-16. Coverage varies by model. Rated module speed is not a guarantee of NAS operating speed; follow the NAS maximum capacity and installation rules.
Looking for cameras compatible with Synology NAS units? See the full Synology camera compatibility database.