IBM 000-8697 What Happens During an Archive

4-30 IBM Informix OnLine Database Server Administrator’s Guide
Write Trailer Page
If the backup was initiated explicitly throughtbtape -a or Auto-Backup,
tbtape looks for another log file with statusU. If another log file requires
backup, the procedure is repeated. Iftbtape cannot find another candidate
for logging, it prompts the operator to indicate if the current log file is to be
backed up. If so, the log files are switched and the backup procedure is
repeated for the formerly current log.
Write Trailer Page
When the entire procedure is complete,tbtape writes a trailer page that
indicates the end of the backup session.
Control is returned to the administrator.
Ifthe tape mounted on LTAPEDEV becomes full before the end of the logical
log file, the operator is prompted for a new tape.
A tape header page is written to the new tape, along with a new log header
page. The page information in the log header contains the number of pages
that remain to be copied to complete the logical log file.
What Happens During an Archive
Archivingcreates a complete record on tape of all used disk pages at a single
point in time. A level-0 archive contains all used disk pages. Level-1 and
level-2 archives are incremental, recording changes since the last archive.
With the information contained on the archive tapes and the logical log
backuptapes, you can re-create the state of OnLine data at some known point
in time.
OnLine creates an archive when the OnLine administrator or operator
requestsone. Archives are not created automatically. Outlined below are the
main steps that are completed during an online archive.
1. tbtape reads archive information from reserved pages.
2. Operator readiesTAPEDEV, the archive tape device.
3. tbtape verifies the archive level requested.
4. tbtape checks that adequate logical log space exists.