A Array Basics - Impediment RS-1600-X24 User Manual

Appendix A
Array Basics
X24 RAID controllers let you set up and manage disk arrays. A disk array (array) is a group of disks that
appears to the system as a single virtual disk. This is accomplished through software resident in the RAID
controller. RAID (Redundant Array of Independent Disks) refers to disk arrays in which part of the array
storage capacity may be used to store redundant information. The redundant information lets you restore
user data if a disk in the array fails.
The host system views the X24 Subsystem as a single FC disk drive. It is actually an array of physical
disks behind a RAID controller. The X24 Subsystem is managed by software to appear as a single, very
large physical disk. Depending on the array type, the virtual disk has advantages in fault-tolerance, cost,
performance, or a combination of these. This section explains the different array types and the disk
requirements for each type.
Tip: Choosing the right RAID level for your needs will improve performance. The following are examples
of storage needs and appropriate RAID level. X24 RAID controllers also provide methods of tracking
statistical data to aid in the process.
Table 1–1 shows some example applications and RAID levels.
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Table 1–1 Example applications and RAID levels
Application
Testing multiple operating systems or software development (where redundancy
is not an issue)
Fast temporary storage or scratch disks for graphics, page layout, and image
rendering
Workgroup servers
Video editing and production
Network operating system, databases, high availability applications, workgroup
servers
Very large databases, Web server, video on demand
Array Basics
RAID level
Volume
RAID 0
RAID 1, 10
RAID 3 or 4
RAID 5
RAID 50
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