Dell PowerVault MD3220 - Manual (Page 42)

42 Planning: MD3200 Series Storage Array Terms and Concepts
RAID 1
RAID 1 uses disk mirroring so that data written to one physical disk is
simultaneously written to another physical disk. This RAID level offers fast
performance, the best data availability, and the highest disk overhead. RAID 1
is recommended for small databases or other applications that do not require
large capacity. RAID 1 provides full data redundancy. For example accounting,
payroll, or financial applications.
RAID 5
RAID 5 uses parity and striping data across all physical disks (distributed
parity) to provide high data throughput and data redundancy, especially for
small random access. This is a versatile RAID level and is suited for multi-user
environments where typical I/O size is small and there is a high proportion of
read activity such as file, application, database, web, e-mail, news, and
intranet servers.
RAID 6
RAID 6 is similar to RAID 5 but provides an additional parity disk for better
redundancy. This is the most versatile RAID level and is suited for multi-user
environments where typical I/O size is small and there is a high proportion of
read activity. RAID 6 is recommended when large size physical disks are used
or large number of physical disks are used in a disk group.
RAID 10
RAID 10, a combination of RAID 1 and RAID 0, uses disk striping across
mirrored disks. It provides high data throughput and complete data
redundancy. Utilizing an even number of physical disks (four or more) creates
a RAID level 10 disk group and/or virtual disk. Because RAID levels 1 and 10
use disk mirroring, half of the capacity of the physical disks is utilized for
mirroring. This leaves the remaining half of the physical disk capacity for
actual storage. RAID 10 is automatically used when a RAID level of 1 is
chosen with four or more physical disks. RAID 10 works well for medium-
sized databases or any environment that requires high performance and fault
tolerance and moderate-to-medium capacity.
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