v5-bay 3.5/2.5 SATA expansion Easily add 5 additional drive bays to Synology DiskStation1. Supporting both 2.5 and 3.5 SATA drives DX517 is a flexible solution supporting on-the-fly volume expansion or serving as a local backup destination. Online volume expansion Managed from DiskStation Manager on the host NAS the additional bays in the DX517 are immediately ready to be used once connected. On-the-fly volume expansion ensures that storage and services on the host are not interrupted during volume expansion. Hot-swappable drive tray design The hot-swappable drive trays of DX517 allow easy drive installation and replacement without powering down the system. Screwless drive tray design reduces the time needed for system setup..