Promise Technology EX8654, EX8658, EX8650, EX4650 manual Technology Background, Introduction to RAID

Chapter 7: Technology Background

•Introduction to RAID (below)

•Choosing a RAID Level (page 232)

•Choosing Stripe Block Size (page 236)

•Choosing Sector Size (page 236)

•Choosing Cache Policy (page 237)

•Capacity Coercion (page 238)

•Initialization (page 239)

•Hot Spare Drive(s) (page 239)

•Partition and Format the Logical Drive (page 240)

•RAID Level Migration (page 240)

•Media Patrol (page 248)

•Predictive Data Migration (PDM) (page 248)

•Transition (page 249)

•Critical & Offline Logical Drives (page 253)

Introduction to RAID

RAID (Redundant Array of Independent Disks) allows multiple physical drives to be combined together in a disk array. Then all or a portion of the disk array is formed into a logical drive. The operating system sees the logical drive as a single storage device, and treats it as such.

The RAID software and controller manage all of the individual drives. The benefits of a RAID can include:

•Higher data transfer rates for increased server performance

•Increased overall storage capacity for a single drive designation (such as, C, D, E, etc.)

•Data redundancy/fault tolerance for ensuring continuous system operation in the event of a hard drive failure

Different types of logical drives use different organizational models and have varying benefits. Also see “Choosing a RAID Level” on page 232. The following outline breaks down the properties for each type of RAID logical drive:

219