What is SHR and should I use it?

SHR (Synology Hybrid RAID) is Synology's automated RAID management layer. It gives you RAID-style redundancy without having to hand-pick a RAID level, and — its headline feature — it uses mixed drive sizes efficiently.

What makes it useful

• Mixed capacities: classic RAID 5 wastes the extra space on larger drives (everything sizes to the smallest). SHR can reclaim much of that when you mix, say, 8 TB and 12 TB drives.
• Easy expansion: replace drives with larger ones one at a time and SHR grows the usable space once the maths allows it.
• Fault tolerance: SHR tolerates one drive failure; SHR-2 tolerates two, for larger arrays.

Should you use it?

For most home and small-office users, yes — SHR is the sensible default. It is flexible, forgiving of mismatched drives, and simple to expand. Choose SHR-2 once you have five or more large drives, where a longer rebuild makes double parity worthwhile.

When to pick classic RAID instead

SHR is Synology-specific. If you might need to move the array to non-Synology hardware, classic RAID (5/6/10) is more portable. You also lose nothing by using classic RAID if all your drives are the same size — the efficiency gain of SHR mainly shows with mixed capacities. Whichever you pick, use CMR NAS drives; the table lists options.