| But what is Raid 0-1-5-10 RAID-0, Disk Spanning RAID-0 is not fault tolerant, there are no redundant drives in a RAID-0 array. Data is striped across two or more physical disks to make one (larger) logical disk. RAID-0 or spanning, is included with other .RAID levels by convention.
Spanning allows a file or a volume to be larger than the size of a single disk. This simplifies file service in some operating systems or applications where a single volume of very large capacity is required. Spans are also called arrays or logical drives. Because the probability of a failure is higher than for a single drive, mirroring or parity is frequently added for fault tolerance.
RAID-1, Disk Mirroring
RAID-1 always uses disks in pairs. A complete copy of a working drive is constantly mirrored to a second drive. If either drive fails, the system continues to work from the other. Mirrored systems require at least two drives, higher .RAID levels require more than two.
This is the most widely used .RAID level. It is found in Industrial, Manufacturing and Communications systems where performance and minimum downtime are critical. PSI specializes in support for OEMs and VARs needing cost effective, high performance fault tolerant systems.
RAID-5, Disk Striping with Parity
When a large file or volume (bigger than a single disk) is required, multiple physical drives are combined to create a larger logical drive. As drives are added, the chance of a drive failure increases. Using parity, missing data can be reconstructed from the remaining data.
Conceptualy, RAID-5 adds parity to a RAID-0 span. Either may be referred to as a span, array or logical drive. Because of parity, N+1 disks are required to store N disks worth of data. Parity adds significant overhead. There is a severe performance penalty when operating with a failed drive.
RAID-10, a Mirrored Span
Where RAID-5 is lower cost, using only one drive to add fault tolerance to a span, RAID-10 goes for more drives, in order to provide more performance. Each drive in the span is duplicated (mirrored). This eliminates the overhead and delay of parity.
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