Can I use any hard drive in a Synology NAS?

You have wide freedom, with two real constraints: recording technology and, on the newest models, DSM policy.

Use CMR, prefer NAS-rated

Any 3.5-inch SATA drive that fits will physically work, but for a NAS you want a CMR NAS drive — IronWolf, WD Red Plus/Pro, Toshiba N300 — or an enterprise CMR drive (Exos, Ultrastar). These are rated for 24/7 operation, tolerate vibration in a multi-bay chassis, and use time-limited error recovery so a slow sector does not get the drive dropped from the array.

What to avoid

• SMR drives (e.g. plain WD Red 2–6 TB, some BarraCuda): they can stall RAID rebuilds.
• Desktop drives for a multi-bay RAID array: low workload ratings and no 24/7 rating age them quickly.

The 2025-model check

On 2025 DiskStation Plus models, confirm your DSM version. DSM 7.3 restored unlisted HDD and 2.5-inch SATA-SSD support; M.2 NVMe still needs a Synology-listed drive there. The carve-out: RackStation Plus and enterprise-series models still require listed HDDs for new storage pools — unlisted HDDs migrate only. On every older model, third-party CMR drives are unrestricted.

Net: a same-or-larger CMR NAS drive is always a safe choice. The table lists current options by price per terabyte.