Side-by-side specifications of the Synology DS108J and DS109, from official datasheets. Differences are highlighted.
| DS108J | DS109 | |
| CPU | Marvell 88F5182 | 1.2GHz |
| Cores / threads | 1/1 | — |
| RAM (base) | 32 MB | 128 MB |
| RAM (max) | 32 MB | 128 MB |
| Drive bays | 1 | 1 |
| Expandable to | 0 | no |
| M.2 slots | 0 | 0 |
| Network | 1x Gigabit | 1x Gigabit |
| 10GbE | no | no |
| Max raw capacity | 1 TB | 2 TB |
| Hot-swap | no | no |
| Form factor | desktop | desktop |
| Released | 2008 | 2008 |
Choose the DS109 if you want a clearly faster, more capable box: it has a 1-bay design too, but with a stronger CPU and more RAM headroom than the DS108J. Neither model offers 10GbE, M.2, or any bay expansion, so the real decision is simply older/lower-end DS108J versus the better-performing DS109 for basic home/SMB file storage.