HP NetRAID Installation and Configuration Guide

Glossary

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modules (OSMs) and hardware device modules (HDMs). I

O increases overall

system performance by shifting I/O computations from the system CPUs to

dedicated I/O processors. It also makes driver management easier and less

expensive.

Initialization: The process of writing zeros to the data fields of a logical drive

and generating corresponding parity to put the logical drive in a Ready state.

Initializing erases previous data, generating parity so that the logical drive will

pass a Consistency Check. Arrays work without initializing, but they may fail a

Consistency Check because parity fields may not have been generated.

IOP: The IOP (I/O Processor) for the integrated HP NetRAID controller directs

all functions of the controller, including command processing, PCI and SCSI bus

transfers, RAID processing, drive rebuilding, cache management, and error

recovery.

Logical Drive: A virtual drive within an array, which may consist of more than

one physical disk.

Logical drives divide up the contiguous storage space of an array of disk modules

or a spanned group of arrays of disks. The storage space in a logical drive is

spread across all the disks in the array or spanned arrays. Each HP NetRAID

Series adapter can be configured with up to eight logical drives in any

combination of sizes. Configure at least one logical drive for each array.

A logical drive can be in one of five states (also see the SCSI Disk Status below):

• Online: all participating disk modules are online.

• Degraded: (Critical) a single disk module in a redundant array (not

RAID 0) is not online. Data loss may result if a second disk module fails.

• Offline: two or more disk modules in a redundant array (not RAID 0), or

one or more disk modules in a RAID 0 array are not online.

• Reconstructing: participating disk modules are being reconstructed.

• Rebuilding: participating disk modules are being rebuilt.

I/O operations can only be performed with logical drives that are online or

degraded (critical).

Logical Volume: A virtual disk made up of logical disks rather than physical

ones. Also called a partition.

LVD SCSI: Low Voltage Differential SCSI.