Operating OnLine 3-105

Start/End Mirroring in a Blobspace or Dbspace

From the Command Line
1. Fromthe command line, change the value of MIRROR to 1. To do this
from the command line, use an editor to edit the file specified by
$INFORMIXDIR/etc/$TBCONFIG.
2. Changethe value of MIRROR to 1. Reinitialize shared memory (take
OnLine offline and then to quiescent mode) for the change to take
effect.
Start/End Mirroring in a Blobspace or Dbspace
This section provides instructions for the following topics:
■Starting mirroring in an existing blobspace or dbspace
■Ending mirroring in an OnLine blobspace or dbspace
Preliminary Considerations
Verifythat the value of MIRROR is set to 1 to enable mirroring. If mirroring is
not enabled, you cannot access the DB-Monitor menu required for either of
these tasks.
You must useDB-Monitor to start or end mirroring. Only user informix can
initiate this action. You can make these changes while OnLine is in online
mode.

Start Mirroring

Youcan create a mirror chunk in either raw or cooked disk space. I/O writes
tomirrors created in cooked disk space exhibit the slowness that is a charac-
teristic of any cooked disk space.
Usethe UNIX link command (ln) to link the actual device names of the mirror
chunksto linked pathnames. In the event of disk failure, you can link a new
device to the pathname. You eliminate the need to physically replace the
device that failed before the chunk is brought back online.
To start mirroring throughDB-Monitor, you must provide a pathname for
each mirror chunk. Specify the linked pathnames, not the actual device
names.