Understanding RAID Levels and Concepts
Single Disk
A single drive can be configured as a unit through 3ware software. (3DM 2 or CLI). Like disks in other RAID configurations, single disks contain 3ware Disk Control Block (DCB) information and are seen by the OS as available units.
Single drives are not fault tolerant and therefore not recommended for high availability systems unless additional precautions are taken to prevent system hangs and data loss.
Hot Spare
A hot spare is a single drive, available online, so that a redundant unit can be automatically rebuilt in case of drive failure.
Determining What RAID Level to Use
Your choice of which type of RAID unit (array) to create will depend on your needs. You may wish to maximize speed of access, total amount of storage, or redundant protection of data. Each type of RAID unit offers a different blend of these characteristics.
The following table provides a brief summary of RAID type characteristics.
Table 2: RAID Configuration Types
RAID Type | Description |
|
|
RAID 0 | Provides performance, but no fault tolerance. |
|
|
RAID 1 | Provides fault tolerance and a read speed advantage over non- |
| RAID disks. |
|
|
RAID 5 | This type of unit provides performance, fault tolerance, and high |
| storage efficiency. |
|
|
RAID 10 | A combination of striped and mirrored units for fault tolerance |
| and high performance. |
|
|
Single Disk | Not a RAID type, but supported as a configuration. |
| Provides for maximum disk capacity with no redundancy. |
|
|
You can create one or more units, depending on the number of drives you have installed.
www.3ware.com | 13 |
