HP LH4r HP NetServer FCArray Assistant - Installation and User Guide - Page 159
Level 5, Level, Levels 00, 10, 30, and 50, RAID Operation
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Appendix B Glossary Level 5 Data is "striped" across several physical drives. For data redundancy, drives are encoded with rotated XOR redundancy. Level 0+1 Combines RAID 0 striping and RAID 1 mirroring. This level provides redundancy through mirroring. Levels 00, 10, 30, and 50 Multi-layer RAID levels, which span RAID levels 0, 1, 3, and 5 by striping data across, drive groups (RAID Drives). JBOD Sometimes referred to as "Just a Bunch of Disks." Each drive is operated independently like a normal disk drive, or drives may be spanned and seen as a single drive. This level does not provide data redundancy. NOTE The host operating system drivers and software utilities remain unchanged regardless of the level of RAID installed. The controller makes the physical configuration and RAID level implementation transparent to the host operating system. RAID Operation RAID Controllers use the host ports to connect to one or more Host Bus Adapters in one or more host computer systems. Depending on the model and configuration of the controller, there may be from one to four host ports. Each configured logical drive consumes a particular bus-target ID LUN on the host system. Multiple sets of disk drives are connected to the controller via its drive channels. There may be as many as six drive channels, depending on the controller model and configuration. In duplex, or Active/Active mode, two identical RAID Controllers are connected to the same hosts via their host ports, to the same drives via their drive channels, and to each other via a special hardware link for heartbeat sensing. This forms a redundant controller system. The two controllers work together handling data traffic and mirror the write data in each other's cache memory. If one of the controllers fails or otherwise becomes non-operational, the surviving controller takes over its responsibilities with no loss of data. 153