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 theMIRROR shared-memory config-
uration parameter is set to 1.
You can change the value ofMIRROR while OnLine is in online mode but it
willnot take effect until you reinitialize shared memory (take OnLine offline
and then to quiescent or online mode).
Ifyou are logged in as user informix, you can make this change from within
DB-Monitoror from the command line. If you are logged in as root, you must
use the command-line option.
Ifyou make the change from within DB-Monitor, you risk inadvertently reini-
tializing OnLine and destroying all data. This risk is present because you
accessthe MIRROR parameter through the Initialize option of the Parameters
menu.
From DB-Monitor
1. From withinDB-Monitor, select the Parameters menu, Initialize
option to enable mirroring. In the field labelledMirror, enter a Y.
PressESC to record changes.
2. Whenthe screen of shared-memory parameters appears, press ESC to
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, respondY (yes).
4. Whena second prompt appears to confirm that you want to continue
(to initialize OnLine disk space and destroy all existing data),
respondN (no).
5. Reinitialize shared memory (take OnLine offline and then to
quiescent mode) for the change to take effect.