IBM 000-8697 ユーザーズマニュアル

IBM Informix OnLine Database Server Administrator’s Guide

Mirroring is not required, but it is strongly recommended. Refer to

for a complete discussion of mirroring and mirroring administration.

Mirroring is a strategy that pairs primary chunks of one defined blobspace or
dbspace with equal-sized mirror chunks. Writes to the primary chunk are
duplicated asynchronously on the mirror chunk.

Any database that has extreme requirements for reliability in the face of
hardware failure should be located in a mirrored dbspace. Above all, the root
dbspace should be mirrored.

The same OnLine database server on the same host machine must manage
both chunks of a mirrored set. Mirroring on disks managed over a network
is not supported. For a complete description of mirroring and how it works,
refer to

The

MIRROR

parameter is a flag that indicates whether mirroring is enabled

for OnLine. The default value of

MIRROR

 is 0, indicating mirroring is

disabled. The alternative value of

MIRROR

 is 1, indicating mirroring is

enabled.

Enable mirroring if you plan to create a mirror for the root dbspace as part of
initialization. Otherwise, leave mirroring disabled. If you later decide to add
mirroring, you can change the parameter value through

DB-M

onitor or by

editing your configuration file. (Refer to

.)

The

MIRRORPATH

 parameter specifies the full pathname of the chunk that

will serve as the mirror for the initial chunk of the root dbspace (

ROOTPATH

).

MIRRORPATH

 should be a link to the chunk pathname of the actual mirror

chunk for the same reasons that

ROOTPATH

 is specified as a link. (Refer to

.) Similarly, you should select a short pathname for the mirror

chunk. No default value is provided, but /dev/mirror_root is one suggestion
for a link pathname.