
1-24 IBM Informix OnLine Database Server Administrator’s Guide
Mirroring Configuration Guidelines
Mirroring Configuration Guidelines
Mirroringisnotrequired,but it isstronglyrecommended.Referto page 4-14
for a complete discussion of mirroring and mirroring administration.
Mirroringis astrategythatpairsprimarychunksofonedefined blobspaceor
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
hardwarefailureshould be located inamirroreddbspace. 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 page 4-14.
MIRROR
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 mirroringif you plan tocreateamirrorfor the rootdbspace as partof
initialization. Otherwise, leavemirroringdisabled. If youlater decide to add
mirroring, you can change the parameter value through DB-Monitor or by
editing your configuration file. (Refer to page 3-104.)
MIRRORPATH
The MIRRORPATH parameter specifies the full pathname of the chunk that
willserveasthemirrorfortheinitialchunkoftherootdbspace(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
page 1-22.) 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.
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