Introduction
The signature and most iconic feature of Unraid is its proprietary disk array structure (Unraid Array). While traditional RAID systems (like RAID 5 or RAID 6) strictly require hard drives of the exact same capacity to avoid wasting space, Unraid shatters all those rules.
Key Highlights
- Mix-and-Match Hard Drives: You can combine an old 2TB drive, an 8TB drive bought on sale, and a massive 14TB drive into the exact same array without any issues. The system will manage the storage space seamlessly.
- Smart Parity Mechanism: Unraid uses one or two dedicated drives as Parity drives (containing error-correction data). Unlike RAID 5, data on each data drive in an Unraid array remains independent files (using XFS or BTRFS filesystems). If a data drive fails, data on other drives remains completely readable, and you simply use the parity drive to rebuild the lost drive.
- Flexible Array Expansion: Adding a new hard drive to the system does not require complex array rebuilding processes. You just plug it in, add it to the array, and the storage space is instantly ready for use.
Summary
The Unraid array solves the classic economic puzzle for personal users: “Buy as many disks as your budget allows, whenever you want, without worrying about mismatched capacities.”
