RAID (Redundant Array of Independent Disks) is a storage technology that combines multiple drives into one logical unit to improve performance, reliability, or both. It works by distributing data across drives using techniques like striping, mirroring, and parity, depending on the RAID level.
🔑 What RAID Is
- Definition: RAID stands for Redundant Array of Independent Disks.
- Purpose: To enhance speed, fault tolerance, or storage capacity by using multiple drives together.
- Types of Drives: Works with both HDDs and SSDs.
1. Data Distribution (Striping)
In this section, you see a Single File being ingested by the RAID controller.
The Logic: The file is chopped into unique, sequential blocks labeled D1 through D6.
The Action: These blocks are "striped" across the available physical drives. Notice that Drive 1 gets D1 and D5, while Drive 2 gets D2 and D6.
The Goal: By spreading the data out, the system avoids putting the entire load on a single disk, which prevents a bottleneck.
2. Parallel Writing
This feature highlights the performance boost of a RAID array.
Simultaneous Operation: Instead of waiting for Drive 1 to finish writing before starting Drive 2, the controller sends data to multiple drives at the exact same time.
The Visual: The green "Data Write" arrows and the clocks signify that the time taken to write four blocks (D1–D4) is roughly the same as writing one block to a single disk.
Multi-Head Operation: Each drive’s physical actuator arm is working independently, multiplying the total "throughput" (speed) of your storage.
3. Redundancy (The Parity Logic)
This is the most critical part of RAID 5. It shows how the system protects your data without just "copying" everything (which would waste 50% of your space).
The Array Status: In the grid, you'll see P1, P2, P3, and P4. These are Parity blocks. Parity is a mathematical "summary" of the data blocks in that same row.
Drive Failure Scenario: The diagram shows Drive 3 has FAILED. We have lost D3 and D7.
The Reconstruction: Look at the XOR icon. RAID doesn't need the original D3 to recover. It takes the surviving data from that row (D1, D2) and the parity (P1) and runs a mathematical formula (Exclusive OR).
The Result: The formula "Calculates D3" and regenerates the missing data perfectly onto a new replacement drive.
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