A simpler approach often used in data warehousing is to create duplicate grid implementations
at primary and secondary sites. Extraction scripts from the source systems
load both data warehouses simultaneously. If one of the target sites fails, ETL remains
queued such that the failed system can be updated once it is recovered.
Complete Site Failure | 283
When the standby database was being used for reporting, archived redo information
from the primary site could not be applied prior to Oracle Database 10g. Recovery
could only continue when the standby database was closed again. This factor had
important implications for the time it took to recover from an outage with the
standby database. Oracle Database 10g introduced a real-time apply, enabling redo
data to be applied at the standby as soon as it was received.
The physical standby database is still more useful as of Oracle Database 11g since by
deploying the Active Data Guard Option you can query the standby database while
the redo apply is active. The implication of all of these enhancements is that youcan
use your disaster recovery database to handle some of your query workload, as a site
for database backups, and as a site to test database changes.
Pages:
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619