Side-by-side specifications of the Synology DS108j and DS109, from official datasheets. Differences are highlighted.
| DS108j | DS109 | |
| CPU | — | 1.2 GHz |
| Cores / threads | — | 1 core / 1 thread |
| RAM (base) | — | 128 MB |
| RAM (max) | — | — |
| Drive bays | 1 | 1 |
| Expandable to | 0 | 0 |
| M.2 slots | 0 | 0 |
| Network | 1GbE | 1× Gigabit Ethernet |
| 10GbE | no | no |
| Max raw capacity | 1 SATA drive | 2 TB |
| Hot-swap | no | no |
| Form factor | Desktop | Desktop |
| Released | 2008 | 2009 |
| Power consumption | 27 W / 10 W | 19 W / 9 W |
| DSM at launch | — | 2.2 |
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.