Database Reference
In-Depth Information
Management Phase
After the database or application has been deployed in production, it's important to ensure that the applications
perform optimally and meet the service levels expected. The integrated view of Oracle Exadata's hardware and
software components in the EM12c console allows DBAs to navigate from the database performance page to the
Oracle Exadata system health page. When Exadata is running correctly without issues, the system health button
attached to the database is green. When Oracle Enterprise Manager detects an error, the system health button turns
red, indicating a problem may be impacting the database availability.
There can be many reasons (for example, load imbalance, ASM-related problems, cell failures, cell configuration
issues, or network-related failures) that can impact Exadata performance. EM12c can help troubleshoot and diagnose
those problems in Exadata and other engineered systems. Automatic Database Diagnostic Monitor (ADDM) and
Automatic Workload Repository (AWR) functionalities of the database are key tools to performance analysis with the
Exadata Database Machine.
ADDM is a core part of the diagnostic infrastructure in the Oracle database. ADDM starts off with the analysis
of snapshots based on key workload metrics taken within the database. These snapshots include critical performance
information pertaining to the database kernel and the database workload as well as at the operating system level.
ADDM runs on a regular basis, and it analyzes this information and makes recommendations on problems that
it identifies.
For example, when there are SQL load issues, the SQL Advisors make recommendations on how to tune the SQL
statements. Also when there are I/O or CPU issues, ADDM gives advice on system resource optimization. And if you
are running a RAC, ADDM analyzes your complete RAC infrastructure, including the interconnect, and offers advice
on how to improve overall performance.
AWR is a built-in repository, contained within the
SYSAUX
tablespace, that every Oracle database maintains about
operational statistics. AWR is the foundation for all self-management functionality in the Oracle database. It is the
primary source of information that keeps historical information on the Oracle database and how it is being used. The
AWR repository and associated snapshots enable the database to make decisions that are specifically tailored for the
environment it is operating in.
EM12c introduced a new tool to explore the Active Session History (ASH) data. ASH Analytics allows DBAs to
analyze performance data across various performance dimensions. This ability to create filters on various dimensions
really simplifies the identification of performance issues.
■
active Session history (aSh) is a pL/SQL package that has to be installed before it can be used. More
information on aSh can be found in Chapter 9.
Note
As shown in Figure
8-17
, the drop-down menu of ASH Analytics allows administrators to explore performance
data by using predefined performance dimension hierarchies.
