IBM 000-8697 Manual Do Utilizador

Operating OnLine

From the 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
$

.

Change the value of

MIRROR

to 1. Reinitialize shared memory (take

OnLine offline and then to quiescent mode) for the change to take
effect.

This section provides instructions for the following topics:

■

Starting mirroring in an existing blobspace or dbspace

■

Ending mirroring in an OnLine blobspace or dbspace

Verify that the value of

MIRROR

is set to 1 to enable mirroring. If mirroring is

not enabled, you cannot access the

DB-M

onitor menu required for either of

these tasks.

You must use

DB-M

onitor to start or end mirroring. Only user informix can

initiate this action. You can make these changes while OnLine is in online
mode.

You can create a mirror chunk in either raw or cooked disk space.

I/O

writes

to mirrors created in cooked disk space exhibit the slowness that is a charac-
teristic of any cooked disk space.

Use the

UNIX

link command (ln) to link the actual device names of the mirror

chunks to 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 through

DB-M

onitor, you must provide a pathname for

each mirror chunk. Specify the linked pathnames, not the actual device
names.