Guidelines For System Disks; Using Rdr For Fault Tolerance - NEC Express5800/320Ma Administrator's Manual

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Guidelines for System Disks

Observe the following guidelines when configuring the system disks.

•

On the system disk, the IPL procedure creates a boot partition, which contains the

operating system and all of its components.

•

You can greatly reduce application downtime when you upgrade software by

installing and using the optional Active Upgrade software. If you do plan to install

and use Active Upgrade software, be sure to keep system files on a separate disk

from data files. See the Express5800/320Ma: Active Upgrade User's Guide for

more information.

Use RDR disk mirroring to configure and create managed disks in the internal storage.

With RDR disk mirroring, you can mirror pairs of physical disks to create RDR virtual

disks. Each pair of mirrored disks constitutes one RDR virtual disk. RDR offers faster

resynchronization of mirrored disks than other mirroring methods after transient failures

or when a single disk is briefly removed from service.

The data on one disk of the RDR virtual disk pair is replicated in full—that is, mirrored

or duplex—on its corresponding partner disk, irrespective of volume or partition layout.

However, an RDR virtual disk may also be simplex; that is, consisting of only one

physical disk. A simplex RDR virtual disk may contain mirrored volumes created using

third-party disk management facilities. If all volumes on a simplex RDR disk are

mirrored with other disks in the system, then the simplex RDR disk is effectively duplex

(mirrored).

If you are upgrading a system's internal disks from a non-RDR to an RDR configuration,

the existing internal disks must provide adequate space for metadata. Metadata is

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Express5800/320Ma: System Administrator's Guide

N O T E

Create a backup of the system disk with which to restart

the system in the unlikely event of a system failure. See

the Express5800/320Ma: Software Installation and

Configuration Guide.

N O T E

In RDR terminology, an individual physical disk is also

called a plex, and an RDR virtual disk is also called a

LUN, for logical unit.

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