Side-by-side specifications of the Synology DS108j and DS109+, from official datasheets. Differences are highlighted.
| DS108j | DS109+ | |
| CPU | — | — |
| Cores / threads | — | — |
| RAM (base) | — | — |
| RAM (max) | — | — |
| Drive bays | 1 | 1 |
| Expandable to | 0 | 0 |
| M.2 slots | 0 | 0 |
| Network | 1GbE | 1GbE |
| 10GbE | no | no |
| Max raw capacity | 1 SATA drive | — |
| Hot-swap | no | no |
| Form factor | Desktop | desktop |
| Released | 2008 | 2009 |
| Power consumption | 27 W / 10 W | 21 W / 12 W |
| DSM at launch | — | 2.1 |
Neither model supports 10GbE or M.2, and both are single-bay NAS units with no bay expansion. The DS109+ is the better choice because it has a faster CPU and higher RAM ceiling than the DS108j; choose it unless you only need basic file storage.