Promise Technology M300i, M500i, M500f, M300p, M500p Technology Background, Introduction to RAID

Chapter 7: Technology Background

•Introduction to RAID (below)

•Choosing a RAID Level (page 247)

•Stripe Size (page 250)

•Sector Size (page 250)

•Cache Policy (page 251)

•Capacity Coercion (page 252)

•Initialization (page 253)

•Hot Spare Drive(s) (page 253)

•Partition and Format the Logical Drive (page 254)

•RAID Level Migration (page 254)

•Media Patrol (page 257)

•Predictive Data Migration (PDM) (page 257)

•Transition (page 258)

Introduction to RAID

RAID (Redundant Array of Independent Disks) allows multiple hard 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/or controller handle all of the individual drives on its own. 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 disk arrays use different organizational models and have varying benefits. Also see Choosing RAID Level on page 247. The following outline breaks down the properties for each type of RAID disk array:

239