Avago Technologies MegaRAID SATA 150-4 (523) - Manual (Page 24)

2-2 Introduction to RAID
Copyright © 2003–2006 by LSI Logic Corporation. All rights reserved.
2.2 RAID Benefits
RAID systems improve data storage reliability and fault tolerance
compared to single-drive storage systems. Data loss resulting from a
hard drive failure can be prevented by reconstructing missing data from
the remaining hard drives. RAID has gained popularity because it
improves I/O performance and increases storage subsystem reliability.
2.3 RAID Functions
Logical drives, also known as virtual disks, are arrays or spanned arrays
that are available to the operating system. The storage space in a logical
drive is spread across all the physical drives in the array.
Note: The maximum logical drive size for all supported RAID
levels (0, 1, 5, 10, and 50) is 2 Tbytes. You can create
multiple logical drives on the same physical disks.
Your SCSI hard drives must be organized into logical drives in an array
and must be able to support the RAID level that you select. Following are
some common RAID functions:
•
Creating hot spare drives.
•
Configuring physical arrays and logical drives.
•
Initializing one or more logical drives.
•
Accessing controllers, logical drives, and physical drives individually.
•
Rebuilding failed hard drives.
•
Verifying that the redundancy data in logical drives using RAID level
1, 5, 10, or 50 is correct.
•
Reconstructing logical drives after changing RAID levels or adding a
hard drive to an array.
•
Selecting a host controller to work on.