Mixing Drive Sizes in a Synology NAS: What Works and What's a Bad Idea
Compatibility data on this site last refreshed 2026-10-29 · reading time ~3 min
You can mix drive sizes, speeds and brands in a Synology NAS. Whether you should depends on your RAID mode and how much performance you're willing to trade for flexibility.
With SHR: mixing is the point
SHR exists precisely for mixed-capacity arrays — it mirrors the small drives and stripes the big ones, wasting far less space than classic RAID. Growing an SHR volume by swapping in larger drives one at a time is a normal, supported workflow.
With classic RAID: mixing wastes space
RAID 5/6 sizes every disk to the smallest member. A 4TB among 16TB drives costs you 12TB per disk of capacity. It works, it's just expensive.
Performance caveats
- The array runs at the speed of its slowest drive in each stripe — a lone 5400rpm SMR unit drags everything
- Mixing CMR and SMR drives in one array is the worst combination: rebuilds stall unpredictably
- Different brands are fine; NAS-class lines from different vendors coexist without issue
The pragmatic rule
Same model drives for a fresh build; mismatched drives are for growing an existing array or reusing what you own. Every drive must still appear on your model's compatibility list — that part doesn't bend.
Quick answers
Can I mix WD and Seagate drives in one Synology?
Yes. Brand mixing is supported and common; keep all drives CMR and NAS-class for consistent behavior.
Can I upgrade one drive at a time to bigger capacities?
With SHR, yes — replace, repair, repeat. Capacity becomes available once enough disks are upgraded.
Check your exact model
Compatibility is per machine and per part number. Pick your model for its full official drive list: