RAID 6
From Pulsed Media Wiki
Contents
RAID 6
RAID 6 is similar to RAID 5 but includes **double distributed parity**, allowing it to tolerate the simultaneous failure of two disks. It requires a minimum of four disks.
How It Works
RAID 6 stores two independent sets of parity data across all drives, improving redundancy and reliability compared to RAID 5. Like RAID 5, data is striped across all disks.
| Disk 1 | Disk 2 | Disk 3 | Disk 4 | Disk 5 |
|---|---|---|---|---|
| Data A | Data B | Parity 1 | Data C | Parity 2 |
| Parity 1 | Data D | Data E | Parity 2 | Data F |
Advantages
- Tolerates failure of up to **two disks**
- High read performance
- Suitable for large arrays with high availability needs
- Better fault tolerance than RAID 5
Disadvantages
- Slower write performance due to dual parity calculations
- Less usable storage (usable capacity = N-2 disks)
- Even slower rebuilds than RAID 5, with greater risk during rebuilds on large disks
Common Use Cases
- Enterprise-grade storage
- NAS devices requiring high fault tolerance
- Backup servers
- Environments with large capacity SATA disks
Comparison Table
| Feature | RAID 5 | RAID 6 | |||||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Minimum Disks | 3 | 4 | Tolerates Disk Failures | 1 | 2 | Read Speed | High | High | Write Speed | Moderate | Slower | Storage Efficiency | (N - 1)/N | (N - 2)/N | Suitable For | General use | Critical systems with high redundancy |
