Synology SHR-1
Synology SHR-1
Synology Hybrid RAID with single parity. Partitions larger drives so every TB contributes when sizes differ. The mixed-drive answer on Synology.
How it works
SHR partitions drives into tiers matching the smallest drive's size. Each tier behaves like an independent RAID 5 (or RAID 1 for 2 drives). When you mix a 4 TB and three 8 TB drives, you get a 4 TB RAID 5 tier across all four, plus a 4 TB RAID 5 tier across the three larger drives. Migrates from RAID 1/5 without rebuild.
Formula: Synology proprietary
Pros / Cons
Pros
- Handles mixed drive sizes elegantly — every TB contributes
- Single-drive fault tolerance
- Migrates from RAID 1/5 without rebuild
- Fully integrated with Synology DSM
- Easy upgrades — replace one drive at a time
Cons
- Synology hardware required
- Variable usable capacity is harder to predict
- Same URE-during-rebuild risk as RAID 5
- Below the surface it's still RAID 5 risk-wise
When to use
Synology NAS with drives of varying sizes, or planned drive upgrades. 2-4 bay Synology with small to mid drives.
When NOT to use
Non-Synology hardware. Drives ≥ 12 TB — use SHR-2 instead. Anyone wanting RAID without Synology lock-in.
Rebuild math example
For the tiered partitions, rebuild time scales with the largest tier. Mixed 4×4TB + 1×8TB pool: largest tier ≈ 4 TB read across remaining drives. Similar URE exposure to a standard RAID 5 of that tier size.