Eight SATA bays and two cache-only NVMe slots on the DS1821+

You get eight full-size SATA bays on the DS1821+ — serious density for a desktop NAS. The two M.2 NVMe slots are cache-only, which feels like a missed opportunity at this scale. Still, eight bays of 3.5-inch and 2.5-inch SATA drives give you plenty of room to work.