Disk Array Management Hardware

Functionality

A dedicated hardware component responsible for managing and presenting multiple physical hard drives or solid-state drives as a single logical unit to the operating system. This aggregation enables various forms of data redundancy and performance enhancement. It offloads processing from the host system's central processing unit (CPU), thereby improving overall system performance.

Key Features

Data Redundancy: Implements different levels to protect against data loss due to drive failure.
Performance Optimization: Improves read and write speeds by striping data across multiple drives.
Hot-Swapping: Allows replacement of failed drives without system downtime (dependent on the specific array level and configuration).
Cache Memory: Utilizes onboard memory to accelerate data access.
Drive Monitoring: Provides monitoring of drive health and alerts for potential failures.

Common Architectures and Interfaces

These components commonly utilize interfaces such as Serial ATA (SATA), Serial Attached SCSI (SAS), or Non-Volatile Memory Express (NVMe) to connect to drives. They can be implemented as:

Add-in Cards: Typically PCI Express (PCIe) cards that plug into the motherboard.
Onboard Solutions: Integrated directly onto the motherboard chipset (often offering limited features).
External Enclosures: Housed in a separate enclosure and connected via interfaces like SAS, Thunderbolt, or USB.

Common Array Levels

Standard Levels

Level 0: Striping; offers increased performance but no redundancy.
Level 1: Mirroring; provides data redundancy by duplicating data on multiple drives.
Level 5: Striping with parity; combines performance benefits of striping with data redundancy through parity information.
Level 6: Striping with dual parity; similar to level 5 but with two parity blocks for increased fault tolerance.
Level 10 (1+0): Combination of mirroring and striping; provides both high performance and high redundancy.

Hybrid Levels

Advanced configurations that combine multiple levels to achieve specific performance and redundancy characteristics. Examples include level 50, 60, etc.

Considerations for Selection

Performance Requirements: Evaluate the specific workload (e.g., database, video editing) to determine the necessary performance characteristics.
Redundancy Needs: Assess the level of data protection required based on the criticality of the data.
Drive Compatibility: Ensure that the component supports the types and number of drives to be used.
Budget: Hardware solutions vary in price depending on features and performance.