Oracle Real Application Clusters 11g Release 2 and Grid Infrastructure Administration
Question No: 31
Which three statements ate true about services and Transparent Application Failover (TAF)?
If TAF has been configured for a service, sessions using that service fail over to a surviving instance when an outage occurs.
The TAF setting on a service can be NONE, BASIC, PRECONNECT, or POSTCONNECT, and overrides any TAF setting in the client connection definition.
TAF can restart a query after failover has completed but for other statements, such as INSERT, UPDATE, or DELETE, the application must resubmit the transaction.
The TAF setting for a client connection overrides any TAF setting in the service definition.
Services simplify the deployment of TAF because by defining a TAF policy for a service, all connections using this service will automatically have TAF enabled.
Answer: A,B,E Explanation:
Services and Transparent Application Failover
Services simplify the deployment of Transparent Application Failover (TAF).
You can define a TAF policy for a service and all connections using this service will automatically have TAF enabled.
The TAF setting on a service can be NONE, BASIC, or PRECONNECT and overrides any TAF setting in the client connection definition.
To define a TAF policy for a service, the srvctl utility can be used as shown below: srvctl modify service -s gl.example.com -q TRUE -P
BASIC -e SELECT -z 180 -w 5 -j LONG
Where -z is the number of retries, -w is the delay between retry attempts and -j is the connection load balancing goal.
When Oracle Net Services establishes a connection to an instance, the connection remains open until the client closes the connection, the instance is shut down, or a failure occurs. If you configure TAF for the connection, then Oracle Database moves the session to a surviving instance when an outage occurs.
TAF can restart a query after failover has completed but for other types of transactions, such as INSERT, UPDATE, or DELETE, the application must roll back the failed transaction and resubmit the transaction. You must re-execute any session customizations, in other words, ALTER SESSION statements, after failover has occurred. However, with TAF, a connection is not moved during normal processing, even if the workload changes over time.
Oracle 11g: RAC and Grid Infrastructure Administration Accelerated 15 – 13
Question No: 32
Which three statements define a cluster?
is a group of independent, but interconnected computers that act as a single system
can be deployed to increase availability and performance
can be deployed to balance a dynamically changing workload
should appear to an application as multiple servers
Explanation: Oracle Real Application Clusters
->Oracle Real Application Clusters (Oracle RAC) is a database clustering technology whose shared storage capabilities allow multiple machines to work in parallel on the same data, reducing processing time significantly. Oracle RAC also offers
resilience, allowing processing to continue in the event of one or more machines being unavailable because of planned or unplanned downtime.
->A computer cluster consists of a set of loosely connected computers that work together so that in many respects they can be viewed as a single system.
->The components of a cluster are usually connected to each other through fast local area networks, each node running its own instance on an operating system.
Computer clusters emerged as a result of convergence of a number of computing trends including the availability of low cost microprocessors, high speed networks, and software for high performance distributed computing.
->Clusters are usually deployed to improve performance and availability over that of
a single computer, while typically being much more cost-effective than single computers of comparable speed or availability
Question No: 33
mounted: DATA and DATA2, but the results of the SHOW PARAMETER ASM_DISKGROUPS command show only DATA as below:
What could have caused the DATA2 dlskgroup to be mounted based on the information injthe V $ASM_DISKGROUP view?
The DATA2 diskgroup contains the database files required to start a database instance that depends on this ASM instance.
The DATA2 diskgroup contains the voting files required for this cluster.
The DATA diskgroup has mirrored objects in the DATA2 diskgroup.
The DATA value In the parameter implies all diskgroup strings starting with data.
The DATA2 diskgroup contains the SPFILE needed to start the ASM instance.
Answer: B Explanation:
Disk Groups Mounted at Startup
At startup, the Oracle ASM instance attempts to mount the following disk groups:
->Disk groups specified in the ASM_DISKGROUPS initialization parameter
->Disk group used by Cluster Synchronization Services (CSS) for voting files
->Disk groups used by Oracle Clusterware for the Oracle Cluster Registry (OCR)
->Disk group used by the Oracle ASM instance to store the ASM server parameter file (SPFILE)
Oracle 11g: RAC and Grid Infrastructure Administration Accelerated 7 – 5
Question No: 34
Examine the following details for a six-Instance RAC database:
What is the most prominent problem indicated by the above output?
high input/output (I/O) delays
CPU saturation and memory depletion
large number of untuned queries from one of the nodes
misconfigured or faulty interconnect
Explanation: In Oracle RAC environments, RDBMS gathers global cache work load statistics which are reported in STATSPACK, AWRs and GRID CONTROL. Global cache lost blocks statistics (quot;gc cr block lostquot; and/or quot;gc current block lostquot;) for each node in the cluster as well as aggregate statistics for the cluster represent a problem or inefficiencies in
packet processing for the interconnect traffic. These statistics should be monitored and evaluated regularly to guarantee efficient interconnect Global Cache and Enqueue Service (GCS/GES) and cluster processing. Any block loss indicates a problem in network packet processing and should be investigated.
->quot;gc cr block lostquot; / quot;gc current block lostquot; in top 5 or significant wait event Secondary:
->SQL traces report multiple gc cr requests / gc current request /
->gc cr multiblock requests with long and uniform elapsed times
->Poor application performance / throughput
->Packet send/receive errors as displayed in ifconfig or vendor supplied utility
->Netstat reports errors/retransmits/reassembly failures
->Node failures and node integration failures
->Abnormal cpu consumption attributed to network processing
As explained above, Lost blocks are generally caused by unreliable Private network. This can be caused by a bad patch or faulty network configuration or hardware issue.
In most cases, gc block lost has been attributed to (a) A missing OS patch (b) Bad network card (c) Bad cable (d) Bad switch (e) One of the network settings.
Oracle Metalink “gc block lost diagnostics [ID 563566.1]”
Question No: 35
Which three are components of Oracle HA Framework for protecting third-party applications using Oracle Clusterware?
Answer: A,B,D Explanation:
Oracle Clusterware HA Components
Oracle 11g: RAC and Grid Infrastructure Administration Accelerated 5 – 4
Question No: 36
Which three statements are true about the management of Oracle Services?
To manage workloads or a group of applications, you can define services for a particular application or a subset of an application#39;s operations.
Similar work can be categorized under services to ease workload management.
Users who share a service should have different service-level requirements.
Oracle Enterprise Manager or SRVCTL should be used to control cluster-managed services, not DBMS_SERVICE.
Explanation: Using Oracle Services
To manage workloads or a group of applications, you can define services that you assign to a particular application or to a subset of an application#39;s operations. You can also group work by type under services. For example, online users can use one service, while batch processing can use another and reporting can use yet another service to connect to the database. Oracle recommends that all users who share a service have the same service level requirements. You can define specific characteristics for services and each service can represent a separate unit of work. There are many options that you can take advantage of when using services. Although you do not have to implement these options, using them helps optimize application performance.
Oracle does not recommend using the DBMS_SERVICE package for use with services used by an Oracle RAC database. Use SRVCTL or Oracle Enterprise Manager to create database services for Oracle RAC.
Oracle Real Application Clusters Administration and Deployment Guide
Question No: 37
Which three fragments will complete this statement correctly? In a cluster environment, an ACFS volume .
Will be automatically mounted by a node on reboot by default
Must be manually mounted after a node reboot
Will be automatically mounted by a node if it is defined as cluster stack startup if it is included in the ACFS mount registry.
Will be automatically mounted to all node if it is defined as cluster resource when dependent cluster resources requires access
Will be automatically mounted to all node in the cluster when the file system is registered
Must be mounted before it can be registered
Answer: A,C,E Explanation:
->The Oracle ACFS mount registry supports both Oracle Restart and Oracle Grid
Infrastructure cluster configurations. File systems that are to be mounted persistently (across reboots) can be registered with the Oracle ACFS mount registry. In cluster configurations, registered Oracle ACFS file systems are automatically mounted by the mount registry, similar to a clusterwide mount table.
By default, an Oracle ACFS file system that is inserted into the cluster mount registry is automatically mounted on all cluster members, including cluster members that are added after the registry addition.
The Oracle ACFS registry resource actions are designed to automatically mount a file system only one time for each Oracle Grid Infrastructure initialization to avoid potential conflicts with administrative actions to dismount a given file system.
Oracle Automatic Storage Management Administrator#39;s Guide
Question No: 38
The Oracle Grid Infrastructure administrator wants to perform daily checks on the integrity of the Clusterware files. Which three steps can be performed to determine the health of the OCR files and voting disks?
Run ocrcheck to verify the health of the OCR file only from the master node, which performs all input/output (I/O) operations on the OCR.
Run grep voting lt;grid_homegt;/log/lt;hostnamegt;/cssd/ocssd.log from any cluster node.
Run cluvfy comp ocr -n all from any cluster node.
Run ocrcheck to verify the health of the OCR file from any cluster node.
Run votecheck to verify the health of the voting disk from any cluster node.
Answer: B,C,D Explanation:
Checking the Integrity of Oracle Clusterware Configuration Files
The following techniques are used to validate the integrity of Oracle Cluster configuration files.
Check the ocssd.log for voting disks issues.
$ grep voting lt;grid_homegt;/log/lt;hostnamegt;/cssd/ocssd.log
Use the cluvfy utility or the ocrcheck command to check the integrity of the OCR.
$ cluvfy comp ocr -n all -verbose
Oracle 11g: RAC and Grid Infrastructure Administration
Question No: 39
The Oracle 11g Release 2 (version 184.108.40.206) ASM instance has a new diskgroup named DATA that is currently not mounted. You log in to a cluster node as the Grid Infrastructure software owner and set the environment variables to point to the ASM instance on that node. Using SQL*Plus, you issue the commands:
CONNECT / AS SYSDBA
ALTER DISKGROUP DATA MOUNT;
The system response is: ERROR at line 1:
ORA-15032: not all alterations performed
ORA-15260: permission denied on ASM disk group How do you diagnose this error?
Check v$asm_operation for operations halted by the error.
Check v$asm_attributes to determine the asm.compatible setting.
Check v$asm_usergroup to determine the owning user group for this diskgroup.
Check v$xs_session_role to determine the role privileges of the current user.
Check the connect string for the privileged role.
Answer: E Explanation: Cause
You have logged in with SYSDBA privilege that is not allowed for ASM operations
Login with SYSASM credentials for ASM operations
MOS [ID 889810.1]
Question No: 40
Your RAC database has a high volume of inserts into the SALES table. Sequence SALES_SEQ is used to generate primary key values.
Examine the following query output:
SQLgt; SELECT sequence_name, min_value, max_value, increment_by, cache_size FROM dba_sequences ;
What would you recommend to improve the response times?
Increasing size of undo tablespaces
increasing sequence cache sizes
Answer: B Explanation:
Oracle Sequences and Index Contention
Indexes with key values generated by sequences tend to be subject to leaf block contention when the insert rate is high. That is because the index leaf block holding the highest key value is changed for every row inserted, as the values are monotonically ascending. In RAC, this may lead to a high rate of current and CR blocks transferred between nodes.
One of the simplest techniques that can be used to limit this overhead is to increase the sequence cache, if you are using Oracle sequences. Because the difference between sequence values generated by different instances increases, successive index block splits tend to create instance affinity to index leaf blocks. For example, suppose that an index key value is generated by a CACHE NOORDER sequence and each index leaf block can hold 500 rows. If the sequence cache is set to 50000, while instance 1 inserts values 1, 2, 3, and so on, instance 2 concurrently inserts 50001, 50002, and so on. After some block splits, each instance writes to a different part of the index tree.
So, what is the ideal value for a sequence cache to avoid inter-instance leaf index block contention, yet minimizing possible gaps? One of the main variables to consider is the insert rate: the higher it is, the higher must be the sequence cache. However, creating a simulation to evaluate the gains for a specific configuration is recommended.
Note: By default, the cache value is 20. Typically, 20 is too small for the preceding example.
Oracle 11g: RAC and Grid Infrastructure Administration Accelerated 14 – 24
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