Available Raid Configurations - 3Ware 9550SXU-12 User Manual

Introducing the 3ware® SAS/SATA RAID Controller

Available RAID Configurations

6
• . Parity works in combination with striping on RAID 5,
Distributed Parity
RAID 6, and RAID 50. Parity information is written to each of the striped
drives, in rotation. Should a failure occur, the data on the failed drive can
be reconstructed from the data on the other drives.
• . The process of exchanging a drive without having to shut
Hot Swap
down the system. This is useful when you need to exchange a defective
drive in a redundant unit.
• The process of removing a unit from a controller and
Array Roaming.
putting it back later, either on the same controller, or a different one, and
having it recognized as a unit. The disks may be attached to different ports
than they were originally attached to, without harm to the data.
For definitions of other terms used throughout the documentation, see the
"Glossary".
RAID is a method of combining several hard drives into one unit. It offers
fault tolerance and higher throughput levels than a single hard drive or group
of independent hard drives. RAID levels 0, 1, 10 and 5 are the most popular.
AMCC's 3ware controllers support RAID 0, 1, 5, 6, 10, 50, and Single Disk.
The information below provides a more in-depth explanation of the different
RAID levels.
For how to configure RAID units, see "Configuring a New Unit" on page 101.
RAID 0
RAID 0 provides improved performance, but no fault tolerance. Since the
data is striped across more than one disk, RAID 0 disk arrays achieve high
transfer rates because they can read and write data on more than one drive
simultaneously. The stripe size is configurable during unit creation. RAID 0
requires a minimum of two drives.
When drives are configured in a striped disk array (see Figure 2), large files
are distributed across the multiple disks using RAID 0 techniques.
Striped disk arrays give exceptional performance, particularly for data
intensive applications such as video editing, computer-aided design and
geographical information systems.
RAID 0 arrays are not fault tolerant. The loss of any drive results in the loss of
all the data in that array, and can even cause a system hang, depending on
your operating system. RAID 0 arrays are not recommended for high
availability systems unless additional precautions are taken to prevent system
hangs and data loss.
3ware SAS/SATA RAID Software User Guide, Version 9.5.1