RAID Levels
There are many RAID levels. Some are common and you will probably know them by heart, but there are also many uncommon RAID levels. Let's check them out.
Common RAID Levels |
• RAID 0 |
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Uncommon RAID Levels |
• NRAID |
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Combined RAID Levels |
• RAID 0+1 (01) |
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Special RAID Levels |
• RAID 5E |
A RAID array will appear as a single large hard disk drive to the operating system. All of the computations associated with creating the RAID array are hidden from the operating system. RAID responds to standard disk commands such as read, write, and format (erasing) like a normal hard drive.
Common RAID Levels
RAID Level 0 |
RAID Level 0 stripes data across all disks without redundancy or parity. This RAID level maximizes data transfer rates and is good for handling large files. Spare drives are not useful for this RAID level. Minimum number of hard drives : 2 |
RAID Level 1 |
RAID Level 1 mirrors data across multiple hard drives. Data on one hard drive is duplicated on another hard drive. If one drive fails, then the data is still available on the mirrored drive. This RAID level has the highest cost per MB of storage and is best suited for smaller capacity applications such as mirroring critical data. Typically, only one drive is mirrored at a time. Spare drives are not really particularly useful for this RAID level. Minimum number of hard drives : 2 |
RAID Level 5 |
RAID Level 5 stripes data and parity information at the block level across all hard drives in the array. Parity is written onto the next available drive rather than a dedicated parity drive. Reads and writes may be performed concurrently. RAID Level 5 also calculates parity during the write cycles, but uses an Exclusive-OR (X-OR) algorithm. This algorithm is best suited for smaller data transfers. Spare drives take over in the event of a drive failure. Minimum number of hard drives : 3 |
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