Chapter 7: Technology Background
This chapter covers the following topics:
•
Introduction to RAID (below)
•
Choosing a RAID Level (page 228)
•
Choosing Stripe Size (page 231)
•
Choosing Sector Size (page 231)
•
Cache Policy (page 232)
•
Capacity Coercion (page 233)
•
Initialization (page 234)
•
Hot Spare Drive(s) (page 234)
•
Partition and Format the Logical Drive (page 235)
•
RAID Level Migration (page 235)
•
Media Patrol (page 238)
•
Predictive Data Migration (PDM) (page 238)
•
Transition (page 239)
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 a RAID Level" on page 228. The following
outline breaks down the properties for each type of RAID disk array:
219