RAID Configuration
Select your RAID level and enter drive specifications to calculate usable capacity, fault tolerance, and performance characteristics.
RAID Level Comparison
Compare characteristics of common RAID levels to choose the best configuration for your needs.
| RAID Level | Min Drives | Usable Capacity | Fault Tolerance | Read Speed | Write Speed | Best For |
|---|---|---|---|---|---|---|
| RAID 0 | 2 | 100% | None | Excellent | Excellent | Performance, temp data |
| RAID 1 | 2 | 50% | 1 drive | Good | Fair | Critical data, small arrays |
| RAID 5 | 3 | (N-1)/N | 1 drive | Very Good | Fair | General purpose, balanced |
| RAID 6 | 4 | (N-2)/N | 2 drives | Very Good | Fair | High reliability, large arrays |
| RAID 10 | 4 | 50% | 1 per mirror | Excellent | Very Good | Performance + redundancy |
How RAID Capacity Works
RAID capacity depends on how data is distributed across drives. Different RAID levels make different trade-offs between capacity, performance, and redundancy.
RAID 0 (Striping)
All drives store unique data. Usable capacity is the sum of all drives. No redundancy means any drive failure loses all data.
Usable = N × Drive Size
RAID 1 (Mirroring)
Every drive is duplicated on another drive. Usable capacity is the size of one drive (or the smallest drive if sizes differ). All drives contain identical copies.
Usable = Drive Size (regardless of N)
RAID 5 (Single Parity)
One drive's worth of capacity is used for parity information distributed across all drives. Parity allows the array to survive one drive failure and reconstruct lost data.
Usable = (N - 1) × Drive Size
RAID 6 (Dual Parity)
Two drives' worth of capacity is used for parity. The array can survive any two simultaneous drive failures. Recommended for arrays with large drives or many drives.
Usable = (N - 2) × Drive Size
RAID 10 (Mirroring + Striping)
Drives are organized into mirrored pairs, then striped. Requires an even number of drives. Usable capacity is half the total raw capacity. Can survive multiple drive failures as long as no mirrored pair loses both drives.
Usable = (N / 2) × Drive Size
Choosing the Right RAID Level
When to use RAID 0
Best for temporary or cache data where performance is critical and data loss is acceptable. Video editing scratch disks, render farms, and gaming load times benefit from RAID 0's speed. Never use for irreplaceable data.
When to use RAID 1
Ideal for critical system drives or small arrays where simplicity and reliability matter more than capacity. Good for boot drives or databases that need fast read access and can tolerate reduced write performance.
When to use RAID 5
The most popular general-purpose RAID level. Good balance of capacity, performance, and redundancy for file servers, NAS devices, and workstations. Requires at least three drives. Avoid with drives larger than 2-4TB due to rebuild time and risk.
When to use RAID 6
Recommended for large capacity arrays or when high reliability is required. The dual parity protects against simultaneous failures and reduces risk during long rebuilds. Essential for arrays with drives over 4TB or more than 8 drives.
When to use RAID 10
Best when both performance and redundancy are priorities. Databases, virtualization hosts, and high-traffic servers benefit from RAID 10's excellent read/write speed and fault tolerance. Requires four drives minimum and uses 50% capacity for redundancy.
Important RAID Considerations
RAID is NOT a backup
RAID protects against drive failure, not data corruption, accidental deletion, malware, theft, fire, or flood. Always maintain separate backups on different media or in a different location. Follow the 3-2-1 backup rule: 3 copies, 2 different media types, 1 offsite.
Drive size recommendations
Use drives of the same size in a RAID array. Mixed sizes will cause the array to use only the capacity of the smallest drive on each disk. For example, one 1TB and three 2TB drives in RAID 5 will be treated as four 1TB drives, wasting 3TB.
Rebuild time and risk
When a drive fails in a redundant RAID array, the array enters a degraded state and must rebuild onto a replacement drive. During rebuild, performance is reduced and the array is vulnerable to additional failures. Larger drives take longer to rebuild, increasing risk. RAID 6 mitigates this with dual parity.
Write performance penalty
RAID 5 and 6 have reduced write performance compared to RAID 0 or 10 because every write requires calculating and storing parity information across multiple drives. RAID 6's dual parity increases the penalty. For write-heavy workloads, consider RAID 10.
Frequently Asked Questions
What is RAID?
RAID (Redundant Array of Independent Disks) is a data storage technology that combines multiple physical disk drives into one logical unit for redundancy, performance, or both. Different RAID levels offer different trade-offs between capacity, speed, and fault tolerance.
Which RAID level should I use?
It depends on your priorities. RAID 0 maximizes capacity and speed but offers no redundancy. RAID 1 mirrors data for safety but uses 50% capacity. RAID 5 balances capacity and redundancy with one drive for parity. RAID 6 survives two drive failures. RAID 10 combines mirroring and striping for performance and redundancy but uses 50% capacity.
How much usable space will I get with RAID 5?
RAID 5 uses the capacity of one drive for parity data. With N drives of equal size, usable capacity is (N-1) × drive size. For example, 4 drives of 1TB each gives 3TB usable (1TB for parity).
What is fault tolerance in RAID?
Fault tolerance is the number of drives that can fail simultaneously without data loss. RAID 0 has zero fault tolerance. RAID 1, 5, and 10 can survive one drive failure. RAID 6 can survive two drive failures.
Does RAID replace backups?
No. RAID protects against drive failure, not data corruption, accidental deletion, malware, or physical disasters. Always maintain separate backups regardless of RAID level.
Can I mix different drive sizes in a RAID array?
Yes, but the array will treat all drives as the size of the smallest drive. For example, mixing 2TB and 1TB drives in RAID 5 will treat both as 1TB drives, wasting the extra space on the larger drive.
What happens during a RAID rebuild?
When a drive fails in a redundant array, you replace it with a new drive and the array rebuilds the lost data using parity or mirror information. During rebuild, the array operates in degraded mode with reduced performance and increased vulnerability. Rebuild time increases with drive size and can take hours or days for large drives.
Why is RAID 5 not recommended for large drives?
Large drives (over 2-4TB) take many hours to rebuild after a failure. During the rebuild, the remaining drives are heavily stressed, increasing the chance of a second failure. If two drives fail in RAID 5, all data is lost. For large drives, RAID 6 is safer because it can survive two failures.
Related Tools
- Data Size Converter — convert between bytes, KB, MB, GB, and TB
- Binary File Size Calculator — convert file sizes between decimal and binary units
- Data Transfer Time Calculator -- estimate transfer time for large files
- Data Rate Converter -- convert between network and storage transfer speeds
Privacy & Limitations
- All calculations run entirely in your browser -- nothing is sent to any server.
- Results are computed using standard formulas and should be verified for critical applications.
Related Tools
View all toolsASCII Table
ASCII codes with decimal, hex, and character lookup
Decimal to Hex Converter
Convert decimal numbers to hexadecimal
UUID Generator
Generate random UUIDs instantly
Binary to Decimal Converter
Convert binary numbers to decimal
Base Converter
Convert numbers between bases 2 and 36
Data Size Converter
Convert between bytes, KB, MB, GB, and TB
Storage RAID Calculator FAQ
What is RAID?
RAID (Redundant Array of Independent Disks) is a data storage technology that combines multiple physical disk drives into one logical unit for redundancy, performance, or both. Different RAID levels offer different trade-offs between capacity, speed, and fault tolerance.
Which RAID level should I use?
It depends on your priorities. RAID 0 maximizes capacity and speed but offers no redundancy. RAID 1 mirrors data for safety but uses 50% capacity. RAID 5 balances capacity and redundancy with one drive for parity. RAID 6 survives two drive failures. RAID 10 combines mirroring and striping for performance and redundancy but uses 50% capacity.
How much usable space will I get with RAID 5?
RAID 5 uses the capacity of one drive for parity data. With N drives of equal size, usable capacity is (N-1) × drive size. For example, 4 drives of 1TB each gives 3TB usable (1TB for parity).
What is fault tolerance in RAID?
Fault tolerance is the number of drives that can fail simultaneously without data loss. RAID 0 has zero fault tolerance. RAID 1, 5, and 10 can survive one drive failure. RAID 6 can survive two drive failures.
Does RAID replace backups?
No. RAID protects against drive failure, not data corruption, accidental deletion, malware, or physical disasters. Always maintain separate backups regardless of RAID level.
Can I mix different drive sizes in a RAID array?
Yes, but the array will treat all drives as the size of the smallest drive. For example, mixing 2TB and 1TB drives in RAID 5 will treat both as 1TB drives, wasting the extra space on the larger drive.
What happens during a RAID rebuild?
When a drive fails in a redundant array, you replace it with a new drive and the array rebuilds the lost data using parity or mirror information. During rebuild, the array operates in degraded mode with reduced performance and increased vulnerability.
Why is RAID 5 not recommended for large drives?
Large drives (over 2-4TB) take many hours to rebuild after a failure. During the rebuild, the remaining drives are heavily stressed, increasing the chance of a second failure. If two drives fail in RAID 5, all data is lost. For large drives, RAID 6 is safer.