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RAID Storage Calculator

Calculate usable storage capacity with different RAID configurations

RAID Storage Calculator
Plan your storage array with accurate capacity calculations

Typically 5-10% for most filesystems

RAID 0 (Striping)
Distributes data across disks for better performance with no redundancy
RAID 1 (Mirroring)
Creates exact copies of data for redundancy
RAID 5 (Striping with Parity)
Distributes parity data across all disks
RAID 6 (Striping with Double Parity)
Uses double parity for higher fault tolerance
RAID 10 (1+0)
Combines mirroring and striping for performance and redundancy
RAID 50 (5+0)
Multiple RAID 5 sets in a RAID 0 configuration
RAID 60 (6+0)
Multiple RAID 6 sets in a RAID 0 configuration
RAIDZ1 (ZFS)
ZFS implementation similar to RAID 5 with better integrity
RAIDZ2 (ZFS)
ZFS implementation similar to RAID 6 with better integrity
RAIDZ3 (ZFS)
ZFS implementation with triple parity for high redundancy
JBOD (Just a Bunch Of Disks)
Simply combines disks with no redundancy or performance improvement
Enter disk information to see storage calculations

RAID Storage Calculator: Estimate Your RAID Capacity

This RAID calculator helps you find out how much storage you really get with RAID. Use it to estimate your storage space, how safe your data is, and how much space you can actually use. Understanding your RAID configuration is essential for building efficient and reliable storage systems.

What is RAID?

RAID (Redundant Array of Independent Disks) is a technology that combines multiple physical disk drives into one logical unit for improved performance, increased storage capacity, or data redundancy. Different RAID levels offer different benefits, balancing factors like speed, protection, and usable capacity.

How to Use This RAID Calculator

  1. Enter the number of disks you plan to use in your RAID array
  2. Enter the capacity of each disk and select the appropriate unit (TB, GB, etc.)
  3. Set the filesystem overhead percentage (typically 5-10%)
  4. Select your desired RAID level from the options provided
  5. View the calculated results showing your usable capacity and reliability details

The calculator shows your results immediately - no need to click a button!

Understanding RAID Levels

Different RAID levels offer different benefits. Some focus on speed, while others focus on keeping your data safe:

  • RAID 0 (Striping): Combines all your hard drives into one big, fast drive. But if one drive fails, you lose all your data.
  • RAID 1 (Mirroring): Mirrors your data across two drives. If one drive fails, the other keeps your data safe. You only get half the total storage space.
  • RAID 5 (Striping with Parity): Uses a special calculation to protect your data. It needs at least three drives and can survive one drive failure.
  • RAID 6 (Double Parity): Similar to RAID 5 but with double protection. Can survive two simultaneous drive failures but requires at least four drives.
  • RAID 10 (1+0): Combines RAID 1 and RAID 0. It mirrors data and spreads it across multiple drives for both speed and safety.
  • ZFS RAID (RAIDZ): ZFS implementation offering better protection against data corruption with various levels of redundancy.

How RAID Affects Storage Capacity

RAID affects your storage capacity because some RAID levels use space for data protection. Here's how different RAID levels impact your usable storage:

RAID LevelUsable Capacity FormulaStorage EfficiencyExample with 4×2TB Disks
RAID 0N × Disk Size100%8TB
RAID 11 × Disk Size50% with 2 disks2TB
RAID 5(N-1) × Disk Size67-94%6TB
RAID 6(N-2) × Disk Size50-90%4TB
RAID 10(N/2) × Disk Size50%4TB

RAID Redundancy and Data Protection

RAID redundancy means having extra copies or parity information for your data. This protects you from losing data if a hard drive fails:

  • No Redundancy (RAID 0): All drives must work for the array to function. One drive failure causes complete data loss.
  • Mirroring (RAID 1, 10): Creates exact copies of data. Can lose specific drives without data loss.
  • Parity (RAID 5, 6): Stores special parity information to reconstruct data if a drive fails.
  • Multiple Parity (RAID 6, RAIDZ3): Can survive multiple simultaneous drive failures.

Important: RAID is not a backup solution! While RAID protects against drive failures, it doesn't protect against accidental deletion, corruption, ransomware, or disasters.

Choosing the Right RAID Level for Different Scenarios

ScenarioRecommended RAID LevelBenefits
Home media serverRAID 5Good balance of storage and protection
Gaming PCRAID 0Faster game loading times
Small business serverRAID 10Speed and data safety
Photo/Video editingRAID 5/10Large storage and fast access
Critical data storageRAID 6Survives two drive failures

RAID Performance Considerations

Different RAID levels impact performance in various ways:

  • Read Performance: RAID 0, 10, and 5 offer improved read speeds by reading from multiple disks simultaneously.
  • Write Performance: RAID 0 and 10 provide the best write performance. RAID 5 and 6 have slower writes due to parity calculations.
  • Rebuild Time: When a drive fails, RAID 1 and 10 rebuild faster than RAID 5 and 6. Larger arrays take longer to rebuild.
  • Disk Size Impact: As disk sizes increase, the chance of encountering another failure during a rebuild increases, especially with RAID 5.

Filesystem Overhead Explained

When formatting drives, the filesystem itself requires some space for its structures and metadata. This overhead reduces the actual usable capacity:

  • Most modern filesystems (NTFS, ext4, XFS) have approximately 3-7% overhead
  • ZFS can use 7-10% for metadata and reserve space
  • Overhead increases as you store many small files rather than fewer large files
  • Some filesystems reserve space for system use (e.g., ext4 reserves 5% by default)

Questions About RAID Storage

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