Which two statements are true regarding the Active Session History (ASH) reports for RAC?
A.
They provide details about Oracle databases for all current sessions, and history of past
session all RAC nodes.
B.
They provide statistics about Oracle databases for the active sessions on all the RAC nodes.
C.
They report on data captured for active sessions. The volume of data is directly related to the
work being performed by sessions.
D.
They report on data captured for active sessions. The volume of data is directly related to the
number of sessions on the system.
Explanation:
ASH report statistics provide details about Oracle Database session activity. Oracle
Database records information about active sessions for all active Oracle RAC instances and
stores this data in the System Global Area (SGA). Any session that is connected to the database
and using CPU is considered an active session. The exception to this is sessions that are waiting
for an event that belongs to the idle wait class. ASH reports present a manageable set of data by
capturing only information about active sessions. The amount of the data is directly related to the
work being performed, rather than the number of sessions allowed on the system.
Oracle Real Application Clusters Administration and Deployment Guide
Active Session History has history information of active sessions, therefore shouldn’t it be A & C?
B & C is correct.
ASH report statistics provide details about Oracle Database session activity. Oracle Database records information about active sessions for all active Oracle RAC instances and stores this data in the System Global Area (SGA). Any session that is connected to the database and using CPU is considered an active session. The exception to this is sessions that are waiting for an event that belongs to the idle wait class.
ASH reports present a manageable set of data by capturing only information about active sessions. The amount of the data is directly related to the work being performed, rather than
the number of sessions allowed on the system. ASH statistics that are gathered over a specified duration can be put into ASH reports.
D60488GC11
Oracle 11g: RAC and Grid Infrastructure Administration Accelerated
Lesson 14
A & C is the correct answer.
Fortunately, looking at performance issues in old sessions is easy with an Oracle Database feature called Active Session History. …So even though a session is no longer present in the database instance, the ASH buffer has captured its information.
checkout: http://www.oracle.com/technetwork/issue-archive/2013/13-jan/o13dba-1871177.html
A is right. details of the session
B is wrong. not statistics
C is right. active sessions
D is wrong. not number of sessions
So A.C. are correct
Answer: B,C
Explanation:
Active Session Session History (ASH) is an integral part of the Oracle Database self-management framework and is useful for diagnosing performance problems in Oracle RAC environments. ASH report statistics provide details about Oracle Database session activity. Oracle Database records information about active sessions for all active Oracle RAC instances and stores this
data in the System Global Area (SGA). Any session that is connected to the database and using CPU is considered an active session. The exception to this is sessions that are waiting for an event that belongs to the idle wait class.
ASH reports present a manageable set of data by capturing only information about active sessions. The amount of the data is directly related to the work being performed, rather than the number of sessions allowed on the system. ASH statistics that are gathered over a specified duration can be put into ASH reports.
Each ASH report is divided into multiple sections to help you identify short-lived performance problems that do not appear in the ADDM analysis. Two ASH report sections that are specific to Oracle RAC are Top Cluster Events and Top Remote Instance.
Oracle 11g: RAC and Grid Infrastructure Administration Accelerated 14 – 43