Introducing the 3ware® SAS/SATA RAID Controller6 3ware SAS/SATA RAID Software User Guide, Version 9.5.1• Distributed Parity. Parity works in combination with striping on RAID 5,RAID 6, and RAID 50. Parity information is written to each of the stripeddrives, in rotation. Should a failure occur, the data on the failed drive canbe reconstructed from the data on the other drives.• Hot Swap. The process of exchanging a drive without having to shutdown the system. This is useful when you need to exchange a defectivedrive in a redundant unit.• Array Roaming. The process of removing a unit from a controller andputting it back later, either on the same controller, or a different one, andhaving it recognized as a unit. The disks may be attached to different portsthan they were originally attached to, without harm to the data.For definitions of other terms used throughout the documentation, see the“Glossary”.Available RAID ConfigurationsRAID is a method of combining several hard drives into one unit. It offersfault tolerance and higher throughput levels than a single hard drive or groupof 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 differentRAID levels.For how to configure RAID units, see “Configuring a New Unit” on page 101.RAID 0RAID 0 provides improved performance, but no fault tolerance. Since thedata is striped across more than one disk, RAID 0 disk arrays achieve hightransfer rates because they can read and write data on more than one drivesimultaneously. The stripe size is configurable during unit creation. RAID 0requires a minimum of two drives.When drives are configured in a striped disk array (see Figure 2), large filesare distributed across the multiple disks using RAID 0 techniques.Striped disk arrays give exceptional performance, particularly for dataintensive applications such as video editing, computer-aided design andgeographical information systems.RAID 0 arrays are not fault tolerant. The loss of any drive results in the loss ofall the data in that array, and can even cause a system hang, depending onyour operating system. RAID 0 arrays are not recommended for highavailability systems unless additional precautions are taken to prevent systemhangs and data loss.
