Avago Technologies 3ware SAS 9750-16i4e - Manual (Page 17)

Understanding RAID Concepts and Levels
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Understanding RAID Concepts and Levels
3ware RAID controllers use RAID (Redundant Array of Independent Disks)
to increase your storage system’s performance and provide fault tolerance
(protection against data loss).
This section includes the following RAID-specific topics:
• “RAID Concepts”
• “Available RAID Configurations” on page 6
• “Determining Which RAID Level to Use” on page 12
RAID Concepts
The following concepts are important to understand when working with a
RAID controller:
• Arrays and Units . In the storage industry, an array refers to two or more
disk drives that appear to the operating system as a single unit. When
working with a RAID controller, unit refers to an array of disks that you
can configured and manage through the 3ware software. You can also use
the 3ware software to configure Single-disk units.
• Mirroring . Mirrored arrays (RAID 1) write data to paired drives
simultaneously. If one drive fails, the data is preserved on the paired
drive. Mirroring provides data protection through redundancy. In
addition, mirroring using a 3ware RAID controller provides improved
performance because the 3ware TwinStor® technology reads from both
drives simultaneously.
• Striping . Striping across disks allows data to be written and accessed on
more than one drive simultaneously. Striping combines each drive’s