How many drive bays does the Synology DS1522+ support, and can it be expanded?

Regarding the Synology: The DS1522+ starts with 5 internal bays, giving it an edge over standard 4-bay models, and supports up to 15 bays by adding two DX517 expansion units. This makes it a sweet spot for growing businesses — enough room for RAID 6 with decent capacity today, and a clear upgrade path without retiring the chassis later.