3.4b - RAID: Professor Messer

Drive configuration

Redundant Array of Independent Disks (RAID)

• RAID: Technology used to combine multiple hard drives into a single unit for improved performance and redundancy.

• THIS IS NOT A BACKUP - RAID uses data that is actively retrieved or stored.

RAID 0 (Striping)

• RAID 0 (Striping): RAID system that takes all available data and splits it evenly onto eight separate blocks (for two hard disks).

• Enhances performance significantly by allowing both simultaneous reading and writing, but it provides no redundancy; if one disk fails, all data in the array is lost.

  • Always think of RAID 0 as 0 redundancy.

RAID 1 (Mirroring)

• RAID 1 (Mirroring): RAID system that duplicates files between two or more physical drives.

• High disk utilization - every file is duplicated, so it requires double disk space compared to RAID 0.

• High redundancy - drive failure results in minimal data loss since an exact copy exists on another drive.

RAID 5 (Striping with parity)

• RAID 5 (Striping with parity): RAID system that separates files into blocks and distributes them across multiple drives, while also storing a single parity block.

• Efficient use of disk space - files aren’t duplicated, but space is still used for parity

• High redundancy - data is available in each drive after failure, but parity calculations may affect performance.

RAID 6 (Double striping with parity)

• RAID 6 (Double striping with parity): RAID system that separates files into blocks and distributes them across multiple drives, while also storing two parity blocks.

• High redundancy - two drives can be removed with no effect on disk space, but additional parity calculations may slow performance.

• More complex compared to RAID 5.

RAID 10/RAID 1+0 (A stripe of mirrors)

• RAID 10 (A stripe of mirrors): Stores all the data on one single drive (RAID 0), but provides a mirror for each of those single drives (RAID 1).

• Requires at least 4 drives.

• High redundancy, high speed

• Requires 4 drives - large storage space required.