Disk Redundancy

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1. What does RAID stand for?
RAID (Redundant Array of Independent Disks) is a storage technology that combines multiple disk drive components into a logical unit. Data is distributed across the drives in one of several ways called "RAID levels", depending on what level of redundancy and performance (via parallel communication) is required. Marketers representing industry RAID manufacturers later attempted to reinvent the term to describe a redundant array of independent disks as a means of dissociating a low-cost expectation from RAID technology. RAID is now used as an umbrella term for computer data storage schemes that can divide and replicate data among multiple physical drives. The physical drives are said to be in a RAID array, which is accessed by the operating system as one single drive. The different schemes or architectures are named by the word RAID followed by a number (e.g., RAID 0, RAID 1). Each scheme provides a different balance between two key goals: increase data reliability and increase input/output performance.

2. When would we use RAID?
RAID is extremely useful if reliability and data redundancy are important to you. Even if you take backups, you will need to take the time to restore those backups and those backups could be hours or days old, resulting in data loss. RAID allows you to survive a drive loss without data loss and in many cases without any downtime. RAID is also useful if you are having disk IO issues, where applications are waiting on the disk to perform tasks. Going with RAID will provide you additional throughput by allowing you to read and write data from multiple drives instead of a single drive.

3. Define the types of RAID
RAID 0 - Never, unless the data has no value to you.
RAID 1 - (Mirroring) - RAID 1 is generally used with a pair of disks. Those disks would identically mirror/copy the data equally across all the drives in the array. The point of RAID 1 is primarily for redundancy. If you...
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