Administrator Guide

RAID 0
CAUTION: Do not attempt to create virtual disk groups exceeding 120 physical disks in a RAID 0 configuration even if
premium feature is activated on your storage array. Exceeding the 120-physical disk limit may cause your storage array
to be unstable.
RAID 0 uses disk striping to provide high data throughput, especially for large files in an environment that requires no data consistency.
RAID 0 breaks the data down into segments and writes each segment to a separate physical disk. I/O performance is greatly improved by
spreading the I/O load across many physical disks. Although it offers the best performance of any RAID level, RAID 0 lacks data
consistency. Choose this option only for non-critical data, because failure of one physical disk results in the loss of all data. Examples of
RAID 0 applications include video editing, image editing, prepress applications, or any application that requires high bandwidth.
RAID 1
RAID 1 uses disk replication so that data written to one physical disk is simultaneously written to another physical disk. RAID 1 offers fast
performance and the best data availability, but also the highest disk overhead. RAID 1 is recommended for small databases or other
applications that do not require large capacity. For example, accounting, payroll, or financial applications. RAID 1 provides full data
consistency.
RAID 5
RAID 5 uses consistency and striping data across all physical disks (distributed consistency) to provide high data throughput and data
consistency, especially for small random access. RAID 5 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 consistency disk for better consistency. RAID 6 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
CAUTION:
Do not attempt to create virtual disk groups exceeding 120 physical disks in a RAID 10 configuration even if
premium feature is activated on your storage array. Exceeding the 120-physical disk limit may cause your storage array
to be unstable.
RAID 10, a combination of RAID 1 and RAID 0, uses disk striping across replicated disks. It provides high data throughput and complete
data consistency. Using 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 replication, half of the capacity of the physical disks is used for replication. 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.
Segment size
Disk striping enables data to be written across multiple physical disks. Disk striping enhances performance because striped disks are
accessed simultaneously.
The segment size or stripe element size specifies the size of data in a stripe written to a single disk. The storage array supports stripe
element sizes of 8 KB, 16 KB, 32 KB, 64 KB, 128 KB, and 256 KB. The default stripe element size is 128 KB.
Stripe width, or depth, refers to the number of disks involved in an array where striping is implemented. For example, a 4-disk group with
disk striping has a stripe width of four.
NOTE: Although disk striping delivers excellent performance, striping alone does not provide data consistency.
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