Database Reference
In-Depth Information
Depending on the number of targets and the amount of history you want to keep you have to set aside quite a
bit of storage for the repository. The official Oracle documentation has dedicated a chapter to the maintenance of the
repository. You should ensure that the network communication between the repository and the OMS is of low-latency
and high-bandwidth quality.
Who Should Look After Enterprise Manager?
Very often the Oracle support team is given the honor of looking after Oracle Enterprise Manager. After all, OEM
is an Oracle product so it should naturally fall into the realm of the database administrator, right? This attitude is
found in many environments, but it can be counter-productive to a successful deployment. Anyone looking after
Enterprise Manager needs knowledge about the architecture, the processes such as the data upload from the agents,
maintenance of the repository database and many more. Furthermore debugging problems with the user-visible
console require knowledge about WebLogic and ultimately how Java Enterprise Applications are deployed.
Oracle has successfully hidden a lot of the configuration details of the WebLogic applications from the user,
but every now and then you still need to know where a specific log-file resides to troubleshoot a problem. For this
reason you should invest in the people that look after Enterprise Manager. They could have a DBA background, but a
Middleware administrator is likely even better suited. As with any complex multi-tier application procedures need to
be developed to define what to do when a problem arises, how to escalate a problem to third line support or—in the
worst case—how to fail over to the disaster recovery site.
Sizing Considerations
An installation of Oracle Enterprise Manager has to be well thought through, since it is potentially such an important
part of the infrastructure! The sizing exercise for the OEM infrastructure is a crucial part of the deployment process.
The following should be taken into account:
Number of managed targets
Latency and bandwidth of the network infrastructure leading to the load
balancer/Management Service
Expected number of concurrent connections to the console
Expected or required availability of the service
The following sections in this chapter assume that repository database and management hosts are physically
separate machines.
Considerations for the Oracle Management Service
Elements such as the number of targets, number of agents, and number of concurrent sessions are important
and directly influence the hardware purchase requests for the OMS. You need to worry less about the target hosts
managed by the agents; you'd hope that they have been sized properly! To be fair they are independent pieces of the
overall infrastructure. Special emphasis needs to be placed on memory and CPU power of the Management Services
hosts. The Oracle documentation is a bit vague, and you should certainly do your own investigations into what you
need. Luckily current CPUs are formidable and offer a lot of processing power per host. Oracle defined three different
types of configuration: small, medium, and large.
Small configuration : A small configuration according to Oracle uses no load balancer, a single
Management Host, monitors less than 1000 targets from 100 agents and supports a maximum
of 10 concurrent sessions. It is quite unlikely that you need to be concerned with such a small
environment, even if you wanted to have one per data center.
 
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