RAID Configurations Explained

Hey everyone,

I've seen a lot of questions lately about different RAID levels and what they mean for performance and redundancy. I thought I'd start a thread to break down the most common RAID configurations (RAID 0, 1, 5, 6, 10) and discuss their pros and cons.

RAID 0 (Striping):

• How it works: Data is split into blocks and written across multiple drives simultaneously.
• Pros: Significantly boosts read/write performance.
• Cons: No redundancy. If one drive fails, all data is lost.
• Best for: Applications where speed is critical and data loss is acceptable (e.g., video editing scratch disks).

RAID 1 (Mirroring):

• How it works: Data is written identically to two or more drives.
• Pros: Excellent redundancy. If one drive fails, the other(s) take over seamlessly. Good read performance.
• Cons: Write performance can be slightly slower than a single drive. Usable capacity is halved (or more).
• Best for: Operating systems, critical applications, situations where uptime and data integrity are paramount.

RAID 5 (Striping with Parity):

• How it works: Data is striped across drives, with parity information distributed across all drives. Requires at least 3 drives.
• Pros: Good balance of performance, capacity, and redundancy. Can withstand a single drive failure.
• Cons: Write performance can be impacted by parity calculation. Rebuild times can be long and performance degrades during rebuild.
• Best for: General-purpose file servers, application servers where a balance is needed.

RAID 6 (Striping with Double Parity):

• How it works: Similar to RAID 5 but uses two independent parity blocks distributed across drives. Requires at least 4 drives.
• Pros: Higher redundancy than RAID 5, can withstand two drive failures.
• Cons: Slower write performance than RAID 5 due to more complex parity calculations. Rebuilds are even longer.
• Best for: Large arrays, mission-critical data where higher fault tolerance is required.

RAID 10 (1+0) (Mirroring plus Striping):

• How it works: Combines RAID 1 and RAID 0. Drives are mirrored, and then those mirrored pairs are striped. Requires at least 4 drives (in pairs).
• Pros: Excellent performance (both read and write) and good redundancy. Faster rebuilds than RAID 5/6.
• Cons: Usable capacity is halved. More expensive due to drive count.
• Best for: High-performance databases, demanding applications, virtualization hosts.

What are your preferred RAID configurations and why? Any tips or specific use cases you'd like to share?

Great breakdown, TechGuru_99! I've primarily used RAID 5 for my home NAS. It offers a decent balance, and I like the idea of parity distributed across all drives. However, I've heard the rebuild times can be brutal on large arrays, especially with modern high-capacity drives. I've been considering moving to RAID 6 or RAID 10 for my next upgrade to mitigate that risk.

Does anyone have experience with RAID 6 rebuilds on arrays larger than, say, 20TB?

Excellent summary! For enterprise environments, RAID 10 is often the gold standard due to its performance and robustness. The main drawback is the 50% capacity utilization, but for critical workloads like SQL databases or VDI, the trade-off is usually worth it. RAID 5 can be adequate for less demanding file servers, but the risk of rebuild failure on large drives is a serious concern. Always ensure you have hot spares ready!

I'm using RAID 0 for my video editing workstation's project drive. The speed boost is insane, allowing me to scrub through 4K footage without any stutter. I know it's risky, so my actual completed projects are backed up to a separate NAS using RAID 1. It's a calculated risk for the performance gain during active editing.