What is 11g RAC?
Oracle Real Application Clusters 11g. INTRODUCTION. Oracle Real Application Clusters (RAC) allows Oracle Database to run any packaged or custom application, unchanged across a set of clustered servers. This provides the highest levels of availability and the most flexible scalability.
What is OCR in RAC?
Oracle Cluster Registry (OCR) The OCR contains cluster and database configuration information for RAC and Cluster Ready Services (CRS) such as the cluster node list, and cluster database instances to node mapping, and CRS application resource profiles. The OCR is a shared file located in a cluster file system.
What is voting disk and OCR in Oracle RAC?
The voting disk is a file that manages information about node membership, and the OCR is a file that manages cluster and Oracle RAC database configuration information. The Oracle Clusterware installation process creates the voting disk and the OCR on shared storage.
What is RAC interview?
RAC stands for Real Application cluster. It is a clustering solution from Oracle Corporation that ensures high availability of databases by providing instance failover, media failover features.
How does RAC database work?
Oracle RAC allows multiple computers to run Oracle RDBMS software simultaneously while accessing a single database, thus providing clustering. In a non-RAC Oracle database, a single instance accesses a single database. The database consists of a collection of data files, control files, and redo logs located on disk.
What is scalability in RAC?
To solve the resource crunch, the RAC database provides additional memory resources as more nodes are added to the clustered database system. A RAC database system provides excellent scalability options for the users. As the need arises, users can expand or add the number of nodes in the cluster.
What is Cache Fusion in RAC?
Oracle RAC Cache Fusion is simply where Oracle RAC transfers data blocks from the buffer cache of one instance to the buffer cache of another instance across the cluster interconnect. Transfers across this private network are in order of magnitude better than disk I/O activity and they help Oracle RAC performance.
Why are there 3 voting discs?
Why we need to keep odd number of voting disks? Oracle expects that you will configure at least 3 voting disks for redundancy purposes. You should always configure an odd number of voting disks >= 3. This is because loss of more than half your voting disks will cause the entire cluster to fail.
What is scan IP and VIP in Oracle RAC?
SCAN virtual IP addresses (VIPs) function like node VIPs. However, unlike node VIPs, SCAN VIPs can run on any node in the cluster. Clients (users or applications) that connect using a SCAN instead of a node VIP name or address do not have to update the list of node names or addresses in their local tnsnames.
How do you troubleshoot RAC problems?
The specific RAC troubleshooting steps will include:
- Review of alert log and trace files.
- Run a RAC AWR report: awrgrpt.
- Check ADR for alerts: automatic_diagnostic.
- Run ADRCI diagnostic commands: ARDCI.
- Run CRS to check cluster status (svrctl): srvctl.
- Run cluster verify: cluvfy.
- Run oracheck: orachk.
How many nodes are in RAC cluster?
Oracle RAC 11g supports up to 100 nodes.
What is one node RAC concept?
Executive Overview. Oracle Real Application Clusters (RAC) One Node is an option to the Oracle Database Enterprise. Edition that was introduced with Oracle Database 11g Release 2. It provides enhanced high availability. for single instance Oracle Databases, protecting them from both, planned and unplanned downtime.
What is global cache in RAC?
GCS is the main controlling process that implements Cache Fusion. GCS tracks the location and the status (mode and role) of the data blocks, as well as the access privileges of various instances.
What is CR image in RAC?
CR Image: A consistent read (CR) block represents a consistent snapshot of the data from a previous point in time. Applying undo/rollback segment information produces consistent read versions.
Where is OCR and Voting disk?
OCR config file “/etc/oracle/ocr. loc” check successful Disk group for ocr location “+DATA” is available on all the nodes Checking OCR backup location “/u01/app/12.1.
What is quorum disk in Oracle RAC?
The Quorum Disk Manager utility is a new feature in Oracle SuperCluster release 2.3. Using this utility, you can create an iSCSI quorum disk on two of the database domains and store a voting file on those two quorum disks.
Why does Oracle RAC have 3 scan?
“In case, a 2-node-cluster is used (for which 3 IPs are still recommended for simplification reasons), one server in the cluster will host two sets of SCAN resources under normal operations.” You don’t need 3 SCAN VIPs.
Why are there 3 scan listeners in Oracle RAC?
It reduces connectivity time for application or web based end users. Normally 3 SCANs are capable enough to handle hundreds of new connections in a span of few seconds. Still if you feel that default 3 SCAN listeners are not enough for your environment then you have an option to add few more scan listeners.
What is Cluvfy in RAC?
Pre-check for database installation — Use the cluvfy stage -pre dbinst command to check the specified nodes before installing or creating an Oracle RAC database to verify that your system meets all of the criteria for installing or creating an Oracle RAC database.
What are the RAC commands used in RAC system?
Below are some of the commands which we have used regularly in our RAC system. There are many more RAC commands for 11gR2/12c Clusterware and Grid Home you must need to know as a DBA..! dbms_output.put_line (‘Running in SHARED/RAC mode.’); dbms_output.put_line (‘Running in EXCLUSIVE mode.’); SQL> START?/rdbms/admin/catclust.sql
What are the commands in AutoCAD?
AutoCAD Commands & Shortcuts. F3 – Object Snap (on/off) F8 – Ortho Mode (on/off) F12 – Dynamic Input (on/off) PDFIMPORT – Converts a PDF into a CAD dwg. GEOGRAPHICLOCATION – Places a true scale Aerial map into your CAD dwg. DC – DESIGN CENTER – Useful for copying items from another drawing (i.e. blocks, layers, styles, layouts).
What are the RAC commands for 11gr2/12c Clusterware?
There are many more RAC commands for 11gR2/12c Clusterware and Grid Home you must need to know as a DBA..! dbms_output.put_line (‘Running in SHARED/RAC mode.’); dbms_output.put_line (‘Running in EXCLUSIVE mode.’);
What is the Hitchhiker’s Guide to AutoCAD basics?
Welcome to The Hitchhiker’s Guide to AutoCAD Basics—your guide to the basic commands that you need to create 2D drawings using AutoCAD or AutoCAD LT. This guide is a great place to get started if you just completed your initial training, or to refresh your memory if you use AutoCAD only occasionally.