Can I mix SMR and CMR drives in a NAS?
You can, but avoid it in a RAID array. During a rebuild the SMR drive's slow sustained writes become the bottleneck and can stall the repair, dragging down the whole array. If you must reuse an SMR drive, keep it out of the RAID pool — use it as a standalone backup volume instead. For the array, use all CMR.
Last verified July 22, 2026 · 2 official sources checked Updated
As an Amazon Associate we earn from qualifying purchases on Amazon.ca.
Mixing is possible but self-defeating in a RAID array. The array is only as dependable as its weakest member during a rebuild, and an SMR drive is the weak member.
The rebuild problem
When the array rebuilds — after a failure or an expansion — every drive writes continuously for hours. An SMR drive's throughput collapses under that load, so it becomes the bottleneck: the rebuild slows to the SMR drive's pace and can stall. In a mixed array you get the capacity of both but the rebuild reliability of the SMR one, which defeats the point of RAID.
If you already have an SMR drive
Do not put it in the RAID pool. Instead use it as a standalone volume — a Basic (single-drive) volume for backups or media you can re-download, where sustained writes are rare and a rebuild never happens. That plays to SMR's strengths (cheap capacity) and avoids its weakness.
For the array
Use all-CMR drives, ideally the same capacity. The table lists in-stock CMR NAS drives by price per terabyte so you can match your existing array.
Drives that solve this
Live Amazon.ca prices in CAD, ranked by price per terabyte. The Recording column is verified against manufacturer documentation.
Related questions
Sources
Every technical claim on this page is checked against manufacturer and standards documentation. Dates are when each source was last reviewed.
- Western Digital — Internal drives CMR/SMR statement — checked 2026-07-22
- Seagate — CMR/SMR drive list — checked 2026-07-22