HP LH4r HP NetServer FCArray Assistant - Installation and User Guide - Page 160

Standby Replacement of Disks Hot Spare

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Appendix B Glossary Replacement Table A replacement table contains information regarding which devices have been replaced by others through standby replacement. Rotated XOR Redundancy This term (also known as "parity" or "consistency data") refers to a method of providing complete data redundancy while requiring only a fraction of the storage capacity of mirroring. In a system configured under RAID 3 or RAID 5 (which require at least three drives), all data and parity blocks are divided between the drives. This method provides reconstruction of the data lost due to a single drive's failure (or removal) by using the data on the remaining drives. In any RAID 3 or RAID 5 array, the capacity allocated to redundancy is the equivalent of one drive. XOR refers to the Boolean "Exclusive-OR" operator. SCSI Drive A disk drive equipped with a SCSI interface (sometimes referred to as a SCSI Disk). Each disk drive will be assigned a SCSI address (or SCSI ID), which is a number from 0 to 7 (0 to 15 under Wide or Ultra SCSI). The SCSI address uniquely identifies the drive on the SCSI bus or Channel. Session Refers to the period of time between any two consecutive system shutdowns. System shutdown may be either a power off/on, or a hardware reset. Simplex Mode See "Single Controller (Simplex) Mode." Single Controller (Simplex) Mode A single controller attached to a set of drives that offers RAID functionality without the controller fault tolerance inherent in dual-active mode. Standard Disk Drive This term refers to a hard disk drive, with a SCSI interface, attached to the host system through a standard disk controller. Standby Replacement of Disks ("Hot Spare") The "Standby Replacement" (or "Hot Spare") is one of the most important features the controller provides to achieve automatic, non-stop service with a high degree of fault-tolerance. The controller will carry out the rebuild operation automatically when a disk drive fails and both of the following conditions are true: 154

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Appendix B
Glossary
154
Replacement Table
A replacement table contains information regarding which devices have been
replaced by others through standby replacement.
Rotated XOR Redundancy
This term (also known as "parity" or "consistency data") refers to a method of
providing complete data redundancy while requiring only a fraction of the storage
capacity of mirroring. In a system configured under RAID 3 or RAID 5 (which
require at least three drives), all data and parity blocks are divided between the
drives. This method provides reconstruction of the data lost due to a single drive’s
failure (or removal) by using the data on the remaining drives. In any RAID 3 or
RAID 5 array, the capacity allocated to redundancy is the equivalent of one drive.
XOR refers to the Boolean "Exclusive-OR" operator.
SCSI Drive
A disk drive equipped with a SCSI interface (sometimes referred to as a SCSI
Disk). Each disk drive will be assigned a SCSI address (or SCSI ID), which is a
number from 0 to 7 (0 to 15 under Wide or Ultra SCSI). The SCSI address
uniquely identifies the drive on the SCSI bus or Channel.
Session
Refers to the period of time between any two consecutive system shutdowns.
System shutdown may be either a power off/on, or a hardware reset.
Simplex Mode
See "Single Controller (Simplex) Mode."
Single Controller (Simplex) Mode
A single controller attached to a set of drives that offers RAID functionality
without the controller fault tolerance inherent in dual-active mode.
Standard Disk Drive
This term refers to a hard disk drive, with a SCSI interface, attached to the host
system through a standard disk controller.
Standby Replacement of Disks (“Hot Spare”)
The "Standby Replacement" (or "Hot Spare") is one of the most important
features the controller provides to achieve automatic, non-stop service with a high
degree of fault-tolerance. The controller will carry out the rebuild operation
automatically when a disk drive fails and both of the following conditions are
true: