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RAID

RAID

Enterprise Resource Center • Knowledge Base

Understand RAID Levels, Redundancy, Capacity & Performance

Learn how RAID combines multiple drives for capacity, performance, redundancy, or a combination of those goals. Explore RAID 0, 1, 5, 6, 10, 50, and 60 along with parity, mirroring, striping, hot spares, rebuilds, controllers, and practical storage-planning considerations.

RAID Levels Fault Tolerance Capacity Planning Storage Performance
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RAID Fundamentals

What Is RAID?

RAID is a method of organizing multiple storage devices into a logical storage arrangement. Depending on the RAID level, data may be striped across drives for performance, mirrored for redundancy, protected with distributed parity, or arranged using combinations of those techniques.

The appropriate RAID level depends on the number and capacity of drives, required usable storage, acceptable fault tolerance, workload characteristics, controller or software implementation, rebuild considerations, and the importance of performance versus storage efficiency.

RAID Building Blocks

Striping, Mirroring & Parity

S

Striping

Striping distributes data across multiple drives. It can increase aggregate storage performance and capacity, but striping by itself does not provide redundancy.

M

Mirroring

Mirroring stores copies of data on multiple drives. Capacity efficiency is lower than pure striping, but mirrored layouts can continue operating after certain member-drive failures.

P

Parity

Parity stores information that can be used to reconstruct data after supported drive failures. RAID 5 uses single parity while RAID 6 uses dual parity.

RAID Level Overview

Common RAID Levels

Each RAID level makes a different tradeoff between usable capacity, redundancy, performance, and implementation complexity.

Striping

RAID 0

Uses striping across all active drives. Provides no drive fault tolerance and prioritizes capacity and aggregate performance.

Mirroring

RAID 1

Mirrors data between drives. Nominal usable capacity is generally limited to one member's capacity within the mirror set.

Single Parity

RAID 5

Uses distributed single parity and can tolerate one member drive failure before redundancy is exhausted.

Dual Parity

RAID 6

Uses dual distributed parity and can tolerate up to two member-drive failures in the array before redundancy is exhausted.

Mirrors + Stripe

RAID 10

Stripes across mirrored pairs. It combines mirrored redundancy with striping and is commonly selected for workloads where performance and resiliency are both priorities.

Striped RAID 5 Groups

RAID 50

Stripes data across multiple RAID 5 groups. Fault tolerance depends on where drive failures occur within the underlying groups.

Striped RAID 6 Groups

RAID 60

Stripes data across multiple RAID 6 groups. Each underlying RAID 6 group provides dual-parity protection.

Interactive Planning Tool

Calculate RAID Capacity, Efficiency, Performance & Cost

Use the Tech Supply Direct RAID Calculator to compare RAID 0, 1, 5, 6, 10, 50, and 60 using your drive count, drive capacity, hot-spare requirements, performance assumptions, and hardware costs.

RAID Knowledge Library

RAID Guides & Technical Topics

This section will expand into detailed RAID articles, comparisons, configuration guidance, and storage-planning references.

RAID 0 Explained Striping, capacity, performance, and why RAID 0 provides no redundancy.
RAID 1 Explained Mirroring, usable capacity, fault tolerance, and common applications.
RAID 5 Explained Single parity, capacity efficiency, write behavior, and rebuild considerations.
RAID 6 Explained Dual parity, two-drive fault tolerance, capacity, and workload considerations.
RAID 10 Explained Mirrored pairs, striping, performance, resiliency, and storage efficiency.
RAID 50 Explained Multiple RAID 5 groups, striping, capacity, and distributed failure risk.
RAID 60 Explained Multiple RAID 6 groups, dual parity, capacity, and large-array resiliency.
RAID 5 vs RAID 6 Compare single and dual parity, capacity overhead, and failure tolerance.
RAID 6 vs RAID 10 Compare parity and mirrored architectures for different workload priorities.
RAID 50 vs RAID 60 Compare nested parity layouts for larger storage arrays.
RAID Hot Spares Explained Understand dedicated spares, automatic rebuilds, and capacity tradeoffs.
RAID Rebuilds Explained Learn what happens after drive replacement and why rebuild time matters.
Hardware RAID vs Software RAID Compare controller-based RAID and host-managed implementations.
RAID vs ZFS Understand why traditional RAID and ZFS storage architecture are not identical.
RAID Write Penalty Learn why parity RAID can require additional I/O operations for small writes.
Storage Design

There Is No Universal “Best” RAID Level

A database server, virtualization host, backup repository, file server, archival system, and high-performance scratch volume may prioritize very different combinations of latency, throughput, capacity, resiliency, and cost. RAID selection should follow the workload and availability requirements.

Data Protection

RAID Redundancy Is Not a Backup

RAID can help maintain availability after supported hardware failures, but it does not protect against every form of data loss. Independent, tested backups remain important for protecting against accidental deletion, corruption, ransomware, catastrophic hardware loss, and other failure scenarios.

Before Choosing a RAID Level

Factors to Consider

Usable Capacity Determine how much raw drive capacity becomes nominal usable storage.
Fault Tolerance Understand how many failures the chosen topology can tolerate and under what conditions.
Workload Profile Random I/O, sequential I/O, read/write mix, block size, and latency requirements matter.
Drive Type HDDs, SAS SSDs, SATA SSDs, and NVMe devices behave differently.
Rebuild Time Drive capacity, workload, controller behavior, and array design influence recovery time.
Controller Limits Controller bandwidth, cache, firmware, interfaces, and supported RAID levels can affect implementation.
Hot Spares Dedicated spares can reduce the delay between a drive failure and the beginning of a rebuild.
Hardware Cost More redundancy generally consumes more raw capacity and can increase cost per usable TB.
Continue Your Research

Related Storage Resources

Planning Enterprise Storage?

Turn RAID Requirements Into the Right Storage Configuration

Tech Supply Direct can help review drive counts, storage capacity, RAID controllers, server platforms, workloads, redundancy requirements, and upgrade options when planning an enterprise storage configuration.