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DataDirect Networks EF2800 FC RAID Storage System User Guide (V 1.0)
A r r a y B a s i c s
B.1
Array Types
Array types are defined by their RAID level, a number from 0 through 5
(a higher RAID level does not necessarily indicate a higher level of
performance or fault tolerance). EF2800 RAID controllers let you
create the types of arrays that have proven to be the most useful for
RAID applications: RAID 0, 1, 10 (also known as mirrored), 3, 4, 5, 50,
and volume sets.
For more detailed information about array types, refer to The RAID
Book: A Storage System Technology Handbook by Paul Massiglia, ISBN
1-879936-90-9 or their web site at www.raid-advisory.com.
B.1.1
RAID 0 (Striped Disks)
In a RAID 0 array, data is distributed, or
striped
, across the disks in the
array. The array appears to the server as one large disk with a capacity
approximately equal to the combined capacity of the physical disks.
Because multiple reads and writes can be handled in parallel, the I/O
performance of the array is much better than that of a single physical
disk.
RAID 0 arrays do not store redundant data, so they are not true RAID
applications. If one disk fails, the entire array fails and all array data is
lost. The fault tolerance of a RAID 0 array, therefore, is less than that of
any single disk in the array. The term RAID 0 is widely used for these
arrays, however, because they are conceptually similar to true RAID
applications.
RAID 1, 10
Workgroup servers
RAID 3 or 4
Video editing and production
RAID 5
Network operating system, databases, high availability
applications, workgroup servers
RAID 50
Very large databases, Web server, video on demand
Figure 75. RAID Levels and Example Applications
RAID Level
Application
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