RAID - mysterious storage magic!

 

RAID - what it is really?

RAID (Redundant Array of Independent Disks) combines multiple drives into one logical volume to improve performance, capacity, or redundancy; choose the RAID level based on whether you prioritize speed (RAID 0), protection (RAID 1/6/10), or a balance (RAID 5/50/60).

What is RAID

RAID groups two or more physical disks into a single logical unit so the system can stripe (split) data, mirror (duplicate) data, or store parity (recovery information) across drives. This lets systems present one large volume while gaining speed, fault tolerance, or both.

Why RAID is useful

RAID improves uptime, throughput, and usable capacity compared with single drives. It can prevent data loss from a single drive failure (depending on level), increase read/write performance for demanding workloads, and simplify storage management by exposing one logical disk to the OS.

Common RAID types and how they work:

• RAID 0 (striping): Splits data across drives for maximum speed; no redundancy; use only when performance matters and data loss is acceptable.

• RAID 1 (mirroring): Exact copy on two drives; simple redundancy and fast reads; capacity = half total raw space.

• RAID 5 (striping with single parity): Good balance of capacity, performance, and redundancy; requires ≥3 drives; can survive one drive failure.

• RAID 6 (double parity): Like RAID 5 but survives two drive failures; requires ≥4 drives; better for large arrays where rebuild risk is higher.

• RAID 10 (1+0): Mirrors then stripes; high performance and redundancy, but costly in raw capacity (50% usable) and needs ≥4 drives.

• Nested RAID (50, 60): Combines striping and parity for larger arrays and higher fault tolerance; used in enterprise environments.

Which RAID is for who and for what:

• Home users / gamers: RAID 1 for simple redundancy or RAID 0 only for scratch performance (with backups).

• Small offices / creatives: RAID 5 or RAID 10 for a mix of capacity, speed, and protection.

• Enterprise / NAS / backup servers: RAID 6, 10, 50/60 to tolerate multiple failures and speed rebuilds on large-capacity drives.

HDD recommendations for RAID

Use enterprise or NAS-rated HDDs with vibration tolerance and TLER/Time-Limited Error Recovery features; for mixed workloads consider SSDs for cache or tiering. Avoid consumer desktop drives in large arrays because they may drop out during long error recovery and trigger rebuilds.

Recommended disk counts, usable space, and filesystems

• RAID 0: ≥2 drives; usable = sum of drives; use for temp/scratch; filesystems: XFS, EXT4, NTFS depending on OS.

• RAID 1: 2 drives; usable = half; filesystems: EXT4, XFS, NTFS.

• RAID 5: ≥3 drives; usable = total − 1 drive; prefer XFS or Btrfs on Linux; Windows uses NTFS or ReFS for large arrays.

• RAID 6: ≥4 drives; usable = total − 2 drives; filesystems: XFS, Btrfs, ReFS for resilience and large-volume handling.

• RAID 10: ≥4 drives; usable = half; filesystems: XFS or EXT4 for Linux; NTFS/ReFS on Windows.

Why RAID matters for data management

RAID reduces downtime and improves throughput for users who manage many files or large datasets; it’s not a substitute for backups but a layer of availability and performance that complements backup and versioning strategies.

If you want, I can recommend a specific RAID level and drive model for your workload (backup, media editing, or NAS) and calculate usable capacity for a given number of drives.