
Operating OnLine 3-49
Plan the Archive Schedule
Minimize Archive Time
You can reduce the number of disk pages that must be copied during an
archivebystoringexplicitlycreatedtemporarytablesinadedicated dbspace
and then dropping that dbspace before you archive.
For example, suppose an application in your environment uses temporary
tables to load data. If you load 250,000 rows into a temporary table and then
laterdeletethattemporarytable,thepagesthatwereallocatedtothetableare
archived. If, however, you create the temporary table in a separate dbspace
dedicated to temporary tables and then dropthe dbspacebefore the archive,
none of the pages is archived.
Online Archives
If the archives must be created online, be aware of some of the inconve-
niences associated with the online archive. Online archive activity forces
pages to remain in the physical log until the archive process, tbtape, has
verified that it has a copy of the unchanged page. In this way, the online
archive can slow checkpoint activity, which can contribute to a loss in
performance.
Single Tape Drive
Ifyou arecreatingan archivewith the onlyavailabletapedevice, you cannot
back up any logical log files until the archive is complete. If the logical log
files fill during the archive, normal OnLine processing halts.
Thisproblemcannotoccurifyoucreateyourarchivesinquiescentmode. But
if youwant tocreate online archives withonly onetape device, you can take
the following precautions:
■ Configure OnLine for a large logical log.
■ Store all explicitly created temporary tables in a dedicated dbspace
and drop that dbspace before each archive.
■ Create the archive when database activity is low.
■ Free as many logical log files as possible before you begin the
archive.
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