Here's a breakdown of fundamental RAID levels with their technical specifications:
// Pseudo-code representation of RAID striping (RAID 0)
function raid0_write(data) {
const stripes = split_data(data, num_disks);
parallel_write(stripes);
}
// RAID 1 mirroring implementation concept
const raid1_handler = {
write: function(data) {
primary_disk.write(data);
secondary_disk.write(data); // Synchronous mirror
}
};
For production environments requiring higher reliability:
- RAID 5: Block-level striping with distributed parity (minimum 3 drives)
- RAID 6: Double distributed parity (minimum 4 drives)
- RAID 10: Nested RAID combining mirroring and striping
Modern filesystem-integrated RAID solutions:
# ZFS pool creation examples
zpool create tank raidz1 sda sdb sdc
zpool create fast mirror sda sdb log nvme0n1
# Monitoring ZFS arrays
zpool status -v
zpool iostat -v 5
| RAID Level | Read Speed | Write Speed | Fault Tolerance |
|---|---|---|---|
| 0 | N× (excellent) | N× (excellent) | None |
| 1 | N× (good) | 1× (poor) | N-1 disks |
| 5 | (N-1)× | 1× (with write hole) | 1 disk |
Database Servers: RAID 10 for OLTP workloads requiring high IOPS
Media Storage: RAID 5/6 for large sequential reads
Development Environments: RAID 0 for temporary build artifacts
// Software RAID example (Linux mdadm)
mdadm --create /dev/md0 --level=5 --raid-devices=3 /dev/sd[b-d]1
mdadm --detail --scan >> /etc/mdadm.conf
# Hardware RAID monitoring (MegaCLI example)
/opt/MegaRAID/MegaCli/MegaCli64 -LDInfo -Lall -aAll
Hot-swap replacement example for RAID 5:
- Identify failed disk:
smartctl -a /dev/sdc - Mark as faulty:
mdadm /dev/md0 --fail /dev/sdc1 - Remove disk:
mdadm /dev/md0 --remove /dev/sdc1 - Add replacement:
mdadm /dev/md0 --add /dev/sdd1
Here are the most widely used RAID levels in enterprise and development environments:
- RAID 0 (Striping) - Maximum performance, no redundancy
- RAID 1 (Mirroring) - Simple redundancy with 100% capacity overhead
- RAID 5 (Striping with Parity) - Balanced approach with single disk fault tolerance
- RAID 6 (Double Parity) - Enhanced protection with two disk fault tolerance
- RAID 10 (1+0) - Combination of mirroring and striping for high performance and redundancy
- RAID-Z (ZFS implementation) - Advanced parity schemes with variable stripe width
Each RAID level offers different performance characteristics:
# Example Linux mdadm command for RAID 5
mdadm --create --verbose /dev/md0 --level=5 --raid-devices=4 /dev/sda1 /dev/sdb1 /dev/sdc1 /dev/sdd1
| RAID Level | Read Performance | Write Performance | Fault Tolerance |
|---|---|---|---|
| RAID 0 | Excellent | Excellent | None |
| RAID 1 | Good | Fair | Single disk |
| RAID 5 | Good | Fair (due to parity calculation) | Single disk |
Development environments often use RAID 0 for temporary storage where speed is critical and data can be easily rebuilt. For production databases, RAID 10 provides the best balance of performance and redundancy.
# ZFS pool creation with RAID-Z2 (similar to RAID 6)
zpool create tank raidz2 /dev/ada0 /dev/ada1 /dev/ada2 /dev/ada3
Modern storage solutions like ZFS implement more sophisticated RAID schemes:
- RAID-Z1: Single parity (similar to RAID 5)
- RAID-Z2: Double parity (similar to RAID 6)
- RAID-Z3: Triple parity for extreme reliability
These implementations handle variable stripe widths and include features like checksumming and automatic repair.
RAID 5/6 arrays with large disks can experience extremely long rebuild times, increasing the risk of additional failures during rebuild. Always monitor disk health and consider hot spares for critical arrays.
# Monitoring RAID health in Linux
cat /proc/mdstat
mdadm --detail /dev/md0