The number of SCSI channels and SCSI hard drives

Components and Features

RAID versions, or levels, are specifications that describe a system for ensuring the availability and stability of data stored on large disk subsystems. A RAID system can be implemented in a number of different levels). PERC 3 supports RAID levels 0, 1, 5, 10 (1+0), and 50 (5+0).

Physical Array

A RAID array is a collection of physical disk drives governed by the RAID management software. A RAID array appears to the host computer as one or more logical drives.

Logical Drive

A logical drive is a partition in a physical array of disks that is made up of contiguous data segments on the physical disks. A logical drive can consist of an entire physical array, more than one entire physical array, a part of an array, parts of more than one array, or a combination of any two of these conditions.

Fault Tolerance

Fault tolerance is the capability of the subsystem to undergo a single failure without compromising data integrity, and processing capability. The RAID controller provides this support through redundant arrays in RAID levels 1, 5, 10 and 50. The system can still work properly even with a single disk failure in an array, through performance can be degraded to some extent.

Fault tolerance is often associated with system availability (high mean time between failure, MTFB) because it allows the system to be available during the failures. However, this means it is also important for the system to be available during the repair of the problem. To make this possible, PERC 3 supports hot spare disks, and the auto-rebuild feature.

Introduction to RAID

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Dell 3 manual Components and Features, Physical Array, Logical Drive, Fault Tolerance