OEM Grid Control RMAN tips
by Rampant author Porus Homi Havewala
Installing and configuring Enterprise Manager
Grid Control is covered in many books and even in the detailed
Oracle Installation manuals and READMEs, but what about the real
use of Enterprise Manager Grid Control? How is it going to help
the DBAS in their day to day activities? What is the practical
use of Enterprise Manager in the real world?
Most DBAs worth their salt know that Oracle
has a powerful tool to backup and recover Oracle Databases. This
tool is Oracle RMAN (Recovery Manager).
Today’s DBA can make a very smart choice – he/she can set
up and schedule RMAN backups via the modern approach of Grid
Control, instead of the older, more time-consuming, manual
method of unix shell scripting and cron jobs.
The traditional approach consists of a number
of manual steps – RMAN backup scripts need to be written,
changed for each new system, and then tested, with changes made
to the schedule in crontab. The estimates supplied by the DBA
implementation team range from 3 to 4 hours to perform these
steps, including customizing the backup script and testing out
the backup script for each installation. This would have to be
done on every new
server that is provisioned in the company. Compressing this time
frame is possible, but a rush job could potentially introduce
human error. The management finally decides on an average time
component of 3 hours per server, so as to allow sufficient time
to the DBA team.
However even 3 hours adds up to a lot – if
there are a number of RMAN deployments happening on projects
every week in a large sized company. DBAs are quite expensive
and their time costs a lot to the business, and this approach
would potentially cost a lot of expensive DBA dollars.
Besides these factors, management must also
consider the maintanance cost aspect of the unix shell scripts.
DBAs familiar with unix shell scripting need to be hired and
retained, or if Perl has been used as the scripting language,
then perl-literate resources are required. Other sites may use
other scripting languages, and since there are no scripting
standards in place, scripts may be written in totally different
ways to do the same job. There may be little or no comments in
the code, and little or no documentation.
After the initial author of the scripts has
moved on to bigger and better things in his career, other new
DBAs inherit the scripts. The newcomers spend a lot of time
first of all understanding the code and logic of the scripts,
and when they feel confident, they try their own enhancements or
code fixes. The scripts start to grow exponentially with every
new DBA that comes on, as more and more maintenance work gets
done, until finally these initially simple scripts start to
resemble a multi-headed monster. Sounds familiar?
The very aim of Oracle Enterprise Manager is
to eliminate such issues. In the book, you will see how to setup
and schedule RMAN backups without hand-written or borrowed
scripts, and without the use of Cron. This will be done by using
Enterprise Manager Grid Control. One example of the RMAN backup
settings screen in the Enterprise Manager Wizards is provided in
the screenshot below:
