I am pretty sure most DBAs and Architects get this question very often. The information is available in the Oracle Enterprise Manager (OEM) documentation, this is a compilation I thought of sharing, might benefit someone out there without spending too much time searching.
When someone says OEM, it could be OEM that comes with database (called OEM Database Control in 11g and called OEM Database Express in 12c), or it could mean OEM used to manage multiple databases and hosts (in 11g, known as OEM Grid Control and in 12c known as OEM Cloud Control – this OEM 11g/12c versions are totally different from the database versions). So, have I confused you enough already? Oracle uses “OEM”, “11g”, “12c” for two products. Let me try to clear this up… (hopefully!).
OEM Database Control 11g
Let me start with 11g database. To manage a 11g database, you can use “Database Control”. With Database Control, only one database can be managed/monitored. During the database creation or upgrade you can configure “Database Control” using the DBUA or DBCA tools. You may also use EMCA to configure. Details here… Configuring Database Control During and After Installation.
For you to use Database Control, the dbconsole process must be running on the database host server. You can start and stop the dbconsole process using emctl. Details here… Administering Database Control.
Access Database Control using your browser – https://hostname:portnumber/em, where hostname is the name of the machine database is running, and port number is 1158 by default. Database users with SELECT_CATALOG_ROLE privilege can access Database Control.
Database Control can manage a RAC database as well. You can access database control for RAC through any of the available nodes (hosts) of the RAC database. The dbconsole should be running on the node(s).
Database Control license is included with your Oracle Database license, irrespective of the Edition of the database. So, it is “FREE“! You are allowed to use and manage all the features licensed in the database through OEM. If you are not licensed for Diagnostic and Tuning (to use ASH and AWR, SQL Tuning Advisor, SQL Access Advisor, etc), it is better to set the parameter CONTROL_MANAGEMENT_PACK_ACCESS to NONE in the Oracle database.
The version of the Database Control is tied to your database version… 11.1.0.x or 11.2.0.x.
OEM Database Express (EM Express) 12c
Similar to Database Control in 11g, the equivalent tool available in Oracle Database 12c is Database Express (also known as EM Express). There are few differences on the capabilities compared to 11g Database Control, but is more aligned to support the features of Oracle Database 12c. The architecture of Database Express is different from Database Control. There is no dbconsole running anymore, Database Express (EM Express) is a web-based database management tool that is built inside the Oracle Database.
EM Express is a servlet built on top of Oracle XML DB. DBCA or DBUA automatically configures the port for Database Express access. You can access Database Express using https://hostname:portnumber/em/ (similar to 11g Database Control). The default port is 5500. To configure the port and XMLDB service manually, you may use the steps here… Configuring the HTTPS Port for EM Express. When you invoke the URL, Database Express is started.
Database Express supports only One database. It could be a non-container database (traditional pre-12c architecture) or multitenant database with multiple pluggable databases. It could be a RAC database too.
Database users having the EM_EXPRESS_BASIC role can connect to EM Express and view the pages in read-only mode. The EM_EXPRESS_ALL role enables users to connect to EM Express and use all the functionality provided by EM Express (read/write access to all EM Express features).
Database Express license is included with your Oracle Database license, irrespective of the Edition of the database. So, it is “FREE“! You are allowed to use and manage all the features licensed in the database through Database Express. If you are not licensed for Diagnostic and Tuning (to use ASH and AWR, SQL Tuning Advisor, SQL Access Advisor, etc), it is better to set the parameter CONTROL_MANAGEMENT_PACK_ACCESS to NONE in the database, also ENABLE_DDL_LOGGING.
The version of the Database Express is tied to your database version… 12.1.0.x.
Oracle Enterprise Manager 11g Grid Control
OEM Grid Control is a standalone product, to manage and monitor multiple Oracle targets. You can install and use OEM Grid Control and its repository database, if you purchase any Oracle product (this is the rule for 12c Cloud Control, so I believe it is true for Grid Control as well though not explicitly stated). OEM is not tied directly to Oracle database. That means, the 11g you see with Grid Control is not the same 11g version you associate with the database. Grid control does not have a 11g Release 2. The versions of Grid Control 11g are 11.1.0.x, there is no 11.2.
Grid Control includes three technical components. Oracle Management Service (OMS) is the brain (the application server), Oracle Management Agent is deployed on each host being monitored by OEM to collect and report target information and Oracle Management Repository database to store the data. A picture and more information on the architecture is here… Enterprise Manager Architecture. So unlike Grid Control and Database Express, you need to procure hardware, install, configure OEM Grid Control.
You need to buy license to use the “packs” that are installed separately or installed by default when you install OEM Grid Control. To view the packs and individually disable the packs that are not licensed, read here… Enabling and Disabling the Oracle Enterprise Manager Packs.
Premier Support for OEM Grid Control 11g ends in April 2015.
Oracle Enterprise Manager Cloud Control 12c
Finally, this is the super product you need to be on, if you do not have it installed already, please do! The name again is little bit confusing. “12c” does not mean it is associated with Oracle 12c database, the “Cloud” does not mean it can manage only virtual environments and cloud platforms.
OEM Cloud Control 12c is the latest release of OEM Grid Control. The name change is Oracle strategy to go with the popular technology! Oracle did the same to database names – 8i/9i for internet, 10g/11g for grid, 12c for cloud.
Are you licensed to use OEM Cloud Control 12c to manage databases and other targets? According to the OEM license document, you are. It says “The base installation of Enterprise Manager Cloud Control 12c includes several features free of charge with the purchase of any Oracle software license or Support contract.” To view the features supported by the “FREE” base installation, read chapter 10 here… Base Enterprise Manager Functionality.
The real power of OEM Cloud Control comes from the packs. You can enable a pack indicator showing beside the links in OEM Cloud Control to easily identify the packs or required license to use the link. It is always better to disable the packs that you are not licensed to use. The instructions to disable are here… Enabling and Disabling the Oracle Enterprise Manager Packs.
In addition to the various licensed “cost option” packs from Oracle, there are several OEM extensions available. These are great extensions to use OEM framework to monitor non-Oracle components. Oracle’s Extensibility Exchange is a library of contributions from Oracle, its trusted partners and power users. Kellyn has a great post on the Extensibility Library. The At-a-Glance view gives you opportunity to filter the extensions by vendor, product management area. A check mark in the “Additional Purchase Required” column indicates you need to pay for this extension.
You should definitely explore the Extensibility Exchange…
Have a wonderful Cloud Control!