Compatible hard drives for Synology DS409slim

This model launched before 2025, so Synology's 2025 drive restrictions never applied — unlisted drives have always worked. The official list below is the vendor's tested matrix: the strongest compatibility signal, not a whitelist. Policy guide →

October 2026 — C3RB3R ransomware campaign. Is the DS409slim at risk? Not by model — by DSM build. If this unit runs DSM below 7.4-90075 / 7.3.2-86009-4 / 7.2.2-72806-9 / 7.2.1-69057-12 (or any DSM 6.x), and its admin interface is reachable from the internet, it is exposed to the ongoing C3RB3R campaign. Check Control Panel → Info Center, update, then run the 12-step lockdown. Files already encrypted with .L0CK3D? Recovery guide — don't reboot first.