Monitoring a Database Instance

Monitoring a Database Instance


Hello, I’m going to show you how to
monitor a database in an Oracle Cloud Database as a Service instance using the Database as a Service Monitor.
When a database is created, network access to the virtual machine
hosting the database is limited to Secure Shell SSH
connections on port 22. This access restrition ensures that
the instance is secured by default. To access the Database as a Service
Monitor, you can either ask your cloud service
administrator to open port 443 or you can use SSH client software such
as PuTTY to create an SSH tunnel to port 443 to
connect securely to the database. Here is a putty connection defined with
an SSH tunnel using port forwarding from local port
443 to port 443 on the destination VM that hosts a cloud database. The
destination is specified using the IP address of the VM concatenated with :443. Once you’ve
opened port 443 or created an SSH tunnel to port 443, navigate to the Oracle Database Cloud
Service Console. Click the Menu icon on the right, beside
the database instance you want to monitor and select Open DBaaS Monitor Console. Notice the
other consoles you can open for Oracle Application Express, GlassFish administration, and Enterprise
Manager Express. Another way to access the DBaaS Monitor console is to click on
the database name you want to monitor and then click the menu icon at the top right of the
page. A new page is open in the browser with
the URL HTTPS, your instance IP address, dbaas_monitor. You are prompted for a username and
password. Enter dbaas_monitor as the
username and whatever password was specified when
your cloud database instance was created. The database monitor console appears and displays generic information about
the status of your database. This monitor home page allows you to
monitor and configure the database as well. Here we see that the database is up and
running, it is using 2.02 gigabytes of storage, there are 44 active and 3 inactive
sessions (the database allows a maximum of 472 open sessions) and there are 19 errors in the alert log
file. To access the monitor page, click the Monitor tab at the top of the
page and select RDBMS or select RDBMS in the monitor section of the page. The
database monitor page displays four sections: Storage, Alert Log, Sessions, and Wait
Events. Each section links to a more detailed
view of the monitored area. Click Storage. Wait a few seconds for the result to appear. The Storage
page displays a breakdown of the storage currently allocated by the database. The inner ring shows the distribution of
the allocated space among the different
tablespaces, while the outer ring represents the used space in each
table space. The outer ring also shows the free space in a tablespace.
To get the details about the segments that use space in one of the tablespaces click the tablespace name on the right of
the page. The tablespace detail page provides an
interactive report on the segments that exist within the
tablespace. Most segments are User objects and they
include tables, large objects, and indexes. Returning to
the database monitor page click Alert Log. An interactive report
displays the entries in the database’s alert log. The alert log is a chronological log of messages
and errors commonly used to learn whether the
background processes have encountered errors. Among the entries you
will find critical errors, administrative operations, process errors,
and other database events. Returning to the database monitor page, click Sessions to view open user
sessions. An interactive report displays
information about all currently open sessions in the database. the topmost table shows summarized data
about each open session. Click on any row in this table to see more detailed data about that
session. Returning to the database monitor page, click Wait Events to view the wait events
in real time. In this example the wait events are essentially those of CPU
consumption, plus a little bit of system i/o in
various weights categorized as “Other”. Returning to the database monitor page, click the Configure tab at the top
of the page and select RDBMS. The database configuration page
displays two sections: Configure Database and Features. The Features section reports the
enablement status of major Oracle database features. In this example, the Oracle Real
Application Clusters option is not enabled, while Application Express, Multimedia, Spatial, OLAP, and XDB are enabled. In the Configure Database section, click
parameter settings to view or modify current parameter
values. The Database Parameters page appears. To modify the value of a parameter,
select the parameter, change its value and click the Save Change button at the top. You have
an opportunity to review your change before applying it. Changes that are
saved to memory will take effect immediately across all sessions but will be lost upon the next instance
shutdown. Changes that are saved to the SP file will take effect upon the next instance
startup and are persistent. And that’s it. You now know how to use the database
monitor. For more information about Oracle Database as a Service, see the documentation and the learning
materials in the Oracle Learning Library. Thank you for watching.

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