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Status: Legacy / discontinued
| Series | x21 Series |
|---|---|
| Bays | 12 |
| CPU | AMD Ryzen V1500B |
| Cores / Threads | 4 / 8 |
| RAM | 4 |
| CPU architecture | x86_64 |
| Support tier | limited |
| Warranty (years) | 3 |
| RAM (max) | 32 |
| Memory slots | 2 |
| Memory generation | DDR4 |
| ECC memory | Supported |
| Memory module type | UDIMM |
| Replaceable memory | Replaceable |
| Network ports | 4x 1GbE |
| PCIe expansion | 1 |
| Drive bay types | 3.5" SATA HDD, 2.5" SATA HDD, 2.5" SATA SSD |
| Hot-swappable bays | yes |
Documents
Compatible Drives
43 drives certified on RS2421+'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.
43certified models
5drive brands
24 TBlargest listed
12with verified extra specs
Certified drives by capacity
0.48 TB4
0.96 TB4
1.92 TB4
2 TB1
3.84 TB4
4 TB7
6 TB1
7 TB1
8 TB6
12 TB3
16 TB3
18 TB1
20 TB3
24 TB1
Show all 43 certified drives
43 shown
| Brand | Model | Capacity | Type | Verified drive details | Status | Firmware |
|---|---|---|---|---|---|---|
| Synology | HAT5320-24T | 24.0 TB | 3.5" NAS HDD | - | Recommended | 1401 |
| Synology | HAT5310-20T | 20.0 TB | 3.5" NAS HDD | - | Recommended | 1401 |
| Synology | HAT3320-20T | 20.0 TB | 3.5" NAS HDD | - | Recommended | 1401 |
| Synology | HAT5320-20T | 20.0 TB | 3.5" NAS HDD | - | Recommended | 1402 |
| Synology | HAT5310-18T | 18.0 TB | 3.5" NAS HDD | - | Recommended | 1401 |
| Synology | HAT5300-16T | 16.0 TB | 3.5" NAS HDD | - | Recommended | 1402 |
| Synology | HAT5310-16T | 16.0 TB | 3.5" NAS HDD | - | Recommended | 1403 |
| Synology | HAT3310-16T | 16.0 TB | 3.5" NAS HDD | - | Recommended | 1402 |
| Synology | HAT5300-12T | 12.0 TB | 3.5" NAS HDD | - | Recommended | 1401 |
| Synology | HAT3300-12T | 12.0 TB | 3.5" NAS HDD | - | Recommended | PL01 |
| Synology | HAT3310-12T | 12.0 TB | 3.5" NAS HDD | - | Recommended | 1402 |
| Synology | HAT3320-8T | 8.0 TB | 3.5" NAS HDD | - | Recommended | 1401 |
| Synology | HAT3310-8T | 8.0 TB | 3.5" NAS HDD | - | Recommended | 1403 |
| Synology | HAT5310-8T | 8.0 TB | 3.5" NAS HDD | - | Recommended | 1402 |
| Synology | HAT5320-8T | 8.0 TB | 3.5" NAS HDD | - | Recommended | 1401 |
| Synology | HAT3300-8T | 8.0 TB | 3.5" NAS HDD | - | Recommended | PL01 |
| Synology | HAT5300-8T | 8.0 TB | 3.5" NAS HDD | - | Recommended | 1401 |
| Synology | SAT5210-7000G | 7.0 TB | 2.5" Enterprise SSD | 5-year warranty | Recommended | SCEMH5.0 |
| Synology | HAT3300-6T | 6.0 TB | 3.5" NAS HDD | - | Recommended | PL01 |
| Western Digital | WD4003FFBX | 4.0 TB | 3.5" NAS HDD | 7200 RPM · 256 MB cache · 5-year warranty | Recommended | - |
| Synology | HAT3300-4T | 4.0 TB | 3.5" NAS HDD | - | Recommended | PL01 |
| Synology | HAT5300-4T | 4.0 TB | 3.5" NAS HDD | - | Recommended | 1403 |
| Synology | HAT5320-4T | 4.0 TB | 3.5" NAS HDD | - | Recommended | 1401 |
| Seagate | ST4000NM002A | 4.0 TB | 3.5" Enterprise HDD | - | Recommended | SN02 |
| Toshiba | MG04ACA400E | 4.0 TB | 3.5" Enterprise HDD | 3-year warranty | Recommended | FP4B |
| HGST | HUS726T4TALE6L4 | 4.0 TB | 3.5" Enterprise HDD | - | Recommended | VKGNW40H |
| Synology | SAT5220-3840G | 3.84 TB | 2.5" Enterprise SSD | - | Recommended | SCEMH5.0 |
| Synology | SAT5200-3840G | 3.84 TB | 2.5" Enterprise SSD | - | Recommended | SCEMJ2.1 |
| Synology | SAT5210-3840G | 3.84 TB | 2.5" Enterprise SSD | 5-year warranty | Recommended | SCEMH3.1 |
| Synology | SAT5221-3840G | 3.84 TB | 2.5" Enterprise SSD | 5-year warranty | Recommended | SCEM16.3 |
| Synology | HAT3300-2T | 2.0 TB | 3.5" NAS HDD | 3-year warranty | Recommended | PL01 |
| Synology | SAT5210-1920G | 1.92 TB | 2.5" Enterprise SSD | 5-year warranty | Recommended | SCEMH3.2 |
| Synology | SAT5220-1920G | 1.92 TB | 2.5" Enterprise SSD | - | Recommended | SCEMH5.0 |
| Synology | SAT5221-1920G | 1.92 TB | 2.5" Enterprise SSD | 5-year warranty | Recommended | SCEM16.3 |
| Synology | SAT5200-1920G | 1.92 TB | 2.5" Enterprise SSD | - | Recommended | SCEMJ2.1 |
| Synology | SAT5200-960G | 0.96 TB | 2.5" Enterprise SSD | - | Recommended | SCEMJ2.1 |
| Synology | SAT5210-960G | 0.96 TB | 2.5" Enterprise SSD | 5-year warranty | Recommended | SCEMH3.2 |
| Synology | SAT5221-960G | 0.96 TB | 2.5" Enterprise SSD | 5-year warranty | Recommended | F3MN902 |
| Synology | SAT5220-960G | 0.96 TB | 2.5" Enterprise SSD | - | Recommended | SCEMH5.0 |
| Synology | SAT5210-480G | 0.48 TB | 2.5" Enterprise SSD | 5-year warranty | Recommended | SCEMH3.1 |
| Synology | SAT5220-480G | 0.48 TB | 2.5" Enterprise SSD | - | Recommended | SCEMH5.0 |
| Synology | SAT5221-480G | 0.48 TB | 2.5" Enterprise SSD | 5-year warranty | Recommended | F3MN902 |
| Synology | SAT5200-480G | 0.48 TB | 2.5" Enterprise SSD | - | 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.
Looking for cameras compatible with Synology NAS units? See the full Synology camera compatibility database.