
4-50 IBM Informix OnLine Database Server Administrator’s Guide
Verify Current Configuration
Verify Current Configuration
As its first task, tbtape reads the root dbspace reserved pages from the first
blockofthetape.Thesepagescontainboththeconfigurationfilevaluesatthe
time of the level-0 archive and a complete listing of all dbspaces and chunks
that were defined at the time. The tbtape process verifies that the current
configurationiscompatible with the configurationinformationcontainedon
the tape. As part of the verification, tbtape displays the list of chunks to the
screen. Press F3 or CTRL-B to continue.
The following message appears:
Verifying physical disk space, please wait.
If the two configurations are not compatible (for example, if the value of
USERS onthetapeis 45 andthevalueofUSERS inthecurrentconfigurationis
30), the restore fails and error messages are returned to the user.
Prompt for Logical Log Backup
If tbtape confirmsthe configuration,it also determinesif anylogical log files
are available on disk. If so, tbtape prompts you if you want to backup these
logical log files.
You must back up the logical log files to tape to roll them forward after the
archiveportionoftherestoreiscomplete.Ifyou do not back upthefilesnow,
the restore procedure overwrites the log file pages and the data is lost.
Entera Y to indicate thatyouwant to backupany logical logfilesand mount
a tape on the logical log backup tape device, LTAPEDEV. Verify that the tape
driveisonlineandpressRETURN.Ifnecessary,tbtapepromptsforadditional
tapes.
The tbtape process backs upeach logicallog file ondisk, whetherthe log file
status is unreleased or backed up (U or U-B). Consequently, this backup
might provide you with an additional copy of a specific logical log file.
This redundancy is harmless and serves as a form of insurance. In any
rollforward, you must have all tapes available, in sequence. Thus, an extra
copy ofthe tapesgains youa fall-backin case of failure orloss andcosts you
only the time of the backup.
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