Data guard:
1. Can Oracle's Data Guard be used on
Standard Edition, and if so how? How can you test that the standby database is
in sync?
Oracle's
Data Guard technology is a layer of software and automation built on top of the
standby database facility. In Oracle Standard Edition it is possible to be a
standby database, and update it *manually*. Roughly, put your production
database in archivelog mode. Create a hotbackup of the database and move it to
the standby machine. Then create a standby controlfile on the production
machine, and ship that file, along with all the archived redolog files to the
standby server. Once you have all these files assembled, place them in their
proper locations, recover the standby database, and you're ready to roll. From
this point on, you must manually ship, and manually apply those archived
redologs to stay in sync with production.
To
test your standby database, make a change to a table on the production server,
and commit the change. Then manually switch a logfile so those changes are
archived. Manually ship the newest archived redolog file, and manually apply it
on the standby database. Then open your standby database in read-only mode, and
select from your changed table to verify those changes are available. Once you're
done, shutdown your standby and startup again in standby mode.
2. What is the difference between Active
Dataguard, and the Logical Standby implementation of 10g dataguard?
Active
dataguard is mostly about the physical standby.
Use
physical standby for testing without compromising protection of the production
system. You can open the physical standby read/write - do some destructive
things in it (drop tables, change data, whatever - run a test - perhaps with
real application testing). While this is happening, redo is still streaming
from production, if production fails - you are covered. Use physical standby
for reporting while in managed recovery mode. Since physical standby supports
all of the datatypes - and logical standby does not (11g added broader support,
but not 100%) - there are times when logical standby isn’t sufficient. It also
permits fast incremental backups when offloading backups to a physical standby
database.
3. What is a Dataguard?
Oracle
Dataguard is a disaster recovery solution from Oracle Corporation that has been
utilized in the industry extensively at times of Primary site failure,
failover, switchover scenarios.
4. What are the uses of Oracle Data Guard?
a)
Oracle Data Guard ensures high availability, data protection, and disaster
recovery for enterprise data.
b)
Data Guard provides a comprehensive set of services that create, maintain,
manage, and monitor one or more standby databases to enable production Oracle
databases to survive disasters and data corruptions.
c) With
Data Guard, administrators can optionally improve production database
performance by offloading resource-intensive backup and reporting operations to
standby systems.
