HP P3410A HP NetRAID Series User Guide - Page 154
Rebuild Rate, Reconstruct, Redundancy, Replacement Disk, SCSI Channel, SCSI Disk Status, Ready, - printers
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Glossary Rebuild Rate: The speed at which a rebuild operation occurs. Each HP NetRAID Series adapter or integrated HP NetRAID controller is assigned a rebuild rate, which specifies the percentage of processor resources to be devoted to rebuild operations. Reconstruct: The act of remaking a logical drive after changing RAID levels. Redundancy: The provision of multiple interchangeable components to perform a single function to cope with failures and errors. Redundancy normally applies to hardware, such as using two or even three computers to do the same job. The computers could all be active all the time, thus giving extra performance through parallel processing and extra availability. Another type of redundancy is for one computer to be active while the others monitor its activity, ready to take over if it failed (warm standby). Alternatively, the "spares" could be kept turned off and only switched on when needed (cold standby). Another common form of hardware redundancy is disk mirroring. Replacement Disk: A disk available for use to replace a failed member disk in a RAID array. SCSI: (Small Computer System Interface) A processor-independent standard for system-level interfacing between a computer and intelligent devices, including hard disks, flexible disks, CD-ROM, printers, and scanners. SCSI can connect up to eight devices to a single adapter (or host adapter) on the computer's bus. SCSI transfers eight bits in parallel in Narrow, or 16 bits in Wide. SCSI Channel: HP NetRAID Series adapters and integrated HP NetRAID controllers control the disk drives via SCSI-2 buses called "channels" over which the system transfers data in Fast/Wide, Ultra/Wide, or Ultra2 SCSI mode. The HP NetRAID-3Si adapter has three channels, and the HP NetRAID-1Si adapter has one channel. In HP NetServer LH 3/3r and LH 4/4r, the integrated HP NetRAID controller can have either one or two channels. In other HP NetServers, the integrated HP NetRAID controller has two channels. SCSI Disk Status: A SCSI disk module (physical drive) can be in one of these six states: • Ready: A powered-on and operational disk that has not been configured. • Online: A powered-on and operational disk. • Hot Spare: A powered-on, stand-by disk ready for use if a disk fails. • Failed: Errors on the disk have caused it to fail, or you have used an HP NetRAID utility to take the drive offline. • Rebuild: A disk to which one or more critical logical drives is restoring data. 148