
3-104 IBM Informix OnLine Database Server Administrator’s Guide
Enable Mirroring
Enable Mirroring
Mirroring activity does not begin until you define mirror chunks for a
dbspace or a blobspace and explicitly start mirroring. Do not enable
mirroring until you are ready to define the mirror chunks.
Mirroring is enabled when the value of the MIRROR shared-memory config-
uration parameter is set to 1.
You can change the value of
MIRROR while OnLine is in online mode but it
will not take effect until youreinitialize shared memory (takeOnLine offline
and then to quiescent or online mode).
If youare logged in asuser informix, you can make this changefrom within
DB-Monitoror fromthe command line.Ifyouareloggedin as root, youmust
use the command-line option.
IfyoumakethechangefromwithinDB-Monitor,youriskinadvertentlyreini-
tializing OnLine and destroying all data. This risk is present because you
accessthe MIRROR parameterthroughtheInitialize option oftheParameters
menu.
From DB-Monitor
1. From within DB-Monitor, select the Parameters menu, Initialize
option to enable mirroring. In the field labelled Mirror, enter a Y.
Press ESC to record changes.
2. Whenthescreenofshared-memoryparametersappears,pressESCto
save the rest of your configuration without changes.
3. When the prompt appears to confirm that you want to save the
changes to your configuration, respond Y (yes).
4. Whenasecondpromptappearstoconfirmthatyouwanttocontinue
(to initialize OnLine disk space and destroy all existing data),
respond N (no).
5. Reinitialize shared memory (take OnLine offline and then to
quiescent mode) for the change to take effect.
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