4-48 IBM Informix OnLine Database Server Administrator’s Guide

Verify OnLine Configuration

Logicallogs files that remain on disk and which have not yet been backed up
can still be included in the restore. As part of the restore procedure, OnLine
prompts you to back up those logical log files to tape, so that they can be
rolledforward after the archive tapes have been restored. (This might not be
true if the disks containing the logs failed.)
Verify OnLine Configuration
During the restore, you cannot reinitialize shared memory, add chunks, or
changetape devices. This means that when you begin the restore, the current
OnLine configuration must be compatible with, and accommodate, all
parameter values that have been assigned since the time of the most-recent
archive.
For guidance, use the copies of the configuration file that you create at the
time of each archive. However, do not blindly set all current parameters to
the same values as were recorded at the last archive. Pay attention to three
different groups of parameters:
■Shared-memory parameters
■Mirroring configuration parameters
■Device parameters
Verify that your current shared-memory parameters are set to themaximum
value assigned since the level-0 archive. For example, if you decreased the
value ofUSERS from 45 to 30 sometime since the level-0 archive, you must
beginthe restore with USERS set at 45, and not at 30, even though the config-
urationfile copy for the last archive might have the value of USERS set at 30.
(If you do not have a record of the maximum value ofUSERS since the level-
0 archive, set the value as high as you think necessary. You might need to
reassign values toBUFFERS,LOCKS, and TBLSPACES as well, since the
minimumvalues for these three parameters are based on the value of USERS.)
Verify that your current mirroring configuration matches the configuration
thatwas in effect at the time of the last level-0 archive. Since Informix recom-
mends that you create a level-0 archive after each change in your mirroring
configuration,this should not be a problem. The most critical parameters are
the mirroring parameters that appear in the OnLine configuration file,
MIRRORPATH andMIRROROFFSET.