World of Oracle DBA

In a RAC database there may contain several instances and the initialization parameters of all of the instances should not have identical setting. In fact the initialization parameters that are critical for database creation and affect certain database operations must have the same value for every instance in an Oracle RAC database. Below is the list of initialization parameters that must have identical settings for all instances in a RAC database. 1)ACTIVE_INSTANCE_COUNT 2)ARCHIVE_LAG_TARGET 3)CLUSTER_DATABASE 4)CLUSTER_DATABASE_INSTANCES 5)COMPATIBLE 6)CONTROL_FILES 7)DB_BLOCK_SIZE 8)DB_DOMAIN 9)DB_FILES 10)DB_NAME 11)DB_RECOVERY_FILE_DEST 12)DB_RECOVERY_FILE_DEST_SIZE 13)DB_UNIQUE_NAME 14)DML_LOCKS (Only if set to zero). 15)INSTANCE_TYPE (RDBMS or ASM) 16)PARALLEL_MAX_SERVERS 17)REMOTE_LOGIN_PASSWORD_FILE 18)UNDO_MANAGEMENT

The Oracle Clusterware comprises several background processes that facilitate cluster operations. These processes or components are the main communication links between the Oracle Clusterware high availability components and the Oracle Database as well as they monitor and manage database operations. Here is the list of major oracle clusterware components or processes. 1)Cluster Synchronization Services (CSS): It manages and controls which nodes are members of the cluster and notify members when a node joins or leaves the cluster. 2)Cluster Ready Services (CRS): It manages high availability operations within a cluster. The CRS process start, stop, monitor and failover operations. It generates events when a resource status changes. When you have installed Oracle RAC, crs monitors the Oracle instance, Listener, and so on, and automatically restarts these components when a failure occurs. 3)Event Management (EVM): It is a background process that publishes events that crs creates. 4)Orac...

Configuring RAW decides in RAC is just similiar as you do configure raw devices for voting disk and OCR. In this example, I have faced a different scenario where in In racnode-1 disk sdb is mapped to sdf in ranode-2 In racnode-1 disk sdc is mapped to sdd in ranode-2 In racnode-1 disk sdd is mapped to sde in ranode-2 First I have created three raw partitions from my raw devices sdb, sdc and sdd of racnode-1 each of 80GB for ASM. [root@racnode-1 ~]# /sbin/fdisk /dev/sdb The number of cylinders for this disk is set to 19581. There is nothing wrong with that, but this is larger than 1024, and could in certain setups cause problems with: 1) software that runs at boot time (e.g., old versions of LILO) 2) booting and partitioning software from other OSs (e.g., DOS FDISK, OS/2 FDISK) Command (m for help): n Command action e extended p primary partition (1-4) p Partition number (1-4): 2 First cylinder (33-19581, default 33): +80000M Last cylinder or +size or +sizeM or +sizeK (9726-19...

In a database whenever you query from V$database to know the name of the database and want to know the name of the instance from v$thread they return similar result. Suppose, SQL> select name from v$database; NAME --------- DBASE SQL> select instance from v$thread; INSTANCE -------------------------------------------------------------------------------- dbase which indicates in the database there is only one instance that is database have a one-to-one relationship between datafiles and the instance. Oracle RAC environments, however, have a one-to-many relationship between datafiles and instances. In RAC environments multiple instances form a single database. The instances can reside on different servers which is referred as nodes in RAC environment. • In RAC environment the set of interconnected instances that allows the servers to work together is called cluster. The physical structures that make up the database must reside on shared storage that is accessible from all servers t...

1)Oracle Universal Installer (OUI)- After configuring the pre-installation tasks of the nodes OUI installs the Oracle Clusterware and the Oracle Database software with Oracle RAC. It also can install oracle software on the other nodes using a network connection. 2)Cluster Verification Utility (CVU)- The CVU is a command-line tool. It is very useful to check the nodes for preinstallation as well as postinstallation requirements of the cluster environment. In fact OUI runs the CVU after the Oracle Clusterware installation to verify the environment. 3)Oracle Enterprise Manager- With EM it is easy to configure RAC environments. It has both the Database Control and Grid Control graphical user interfaces (GUIs). 4)Server Control (SRVCTL)- SRVCTL is a command-line interface that you can use to manage an Oracle RAC database from a single point. Using SRVCTL you can start or stop or manage any instance on the cluster. 5)Cluster Ready Services Control (CRSCTL)- CRSCTL is a command-line tool...

1)Checking the Hardware Requirements •Physical memory: At least 1GB RAM. •Swap space: If RAM is between 1 GB and 2 GB then make swap space to 1.5 times of the size of RAM. If RMAN is more than 2GB then make swap space to the equal of the size of the RAM. •Temporary space: At least 400 MB. Typically in /tmp directory. •Processor type (CPU): Need to be certified with the version of the Oracle software being installed. •Hard Disk Space: 1.5 GB for oracle database home directory+1.5GB for the ASM home directory+120 oracle clusterware software installation+Two Oracle Clusterware components OCR 256 MB each, or 512 MB total disk space+Three Oracle Clusterware components Voting Disk 256 MB each, or 768 MB total disk space. •All the nodes in the cluster must have same hardware architecture. However can have machines of different speeds and size in the same cluster. On *nix system you can check hardware components as follows. •To determine physical RAM size, # grep MemTotal /proc/meminfo •To...

Configuring Operating System Users and Groups in All Nodes On windows you don't need to create separate user to install oracle or don't need to create groups. OUI automatically do it. However on unix you must create the following operating system groups are required if you are installing Oracle RAC for the first time. •The OSDBA group (typically, dba) -This is the OS user who has SYSDBA privilege. •The Oracle Inventory group (typically, oinstall) -This group owns all Oracle software installed on the system. The following operating system users are required •A user that owns the Oracle software (typically, oracle). •An unprivileged user (for example, the nobody user on Linux systems). Create the required groups and users Do this steps on all nodes of your cluster. As a root user, /usr/sbin/groupadd oinstall /usr/sbin/groupadd dba useradd -u 200 -g oinstall -G dba -d /home/oracle -r oracle Change the password by, passwd oracle Verify the user by, id oracle Note that in this examp...

Checking the Network Setup with CVU To verify node connectivity among all nodes in your cluster use following syntax as an oracle user, /mount_point/crs/Disk1/cluvfy/runcluvfy.sh comp nodecon -n node_list [-verbose] If you have two nodes node1 and node2 and your mountpoint is /dev/cdrom then enter following command. /dev/cdrom/crs/Disk1/cluvfy/runcluvfy.sh comp nodecon -n node1,node2 -verbose Checking the Hardware and Operating System Setup with CV As an oracle user use the following command syntax to start Cluster Verification Utility (CVU) stage verification to check hardware and OS setup: /mountpoint/crs/Disk1/cluvfy/runcluvfy.sh stage –post hwos –n node_list [-verbose] If you have two nodes node1 and node2 and your mountpoint is /dev/cdrom then enter following command, /dev/cdrom/crs/Disk1/cluvfy/runcluvfy.sh stage –post hwos –n node1,node2 Checking the Operating System Requirements Setup with CVU To check if your system meets the operating system requirement pre-installation tasks...

1)Determine public node names, private node names, and virtual node names for each node in the cluster. For the public node name, use the primary host name of each node. In my environment my one node name is racnode-1 and another node name is racnode-2. So I determine the public, private and virtual node name for node racnode-1 as racnode-1, racnode-1-priv and racnode-1-vip accordingly. Similarly on racnode-2 as racnode-2, racnode-2-priv and racnode-2-vip accordingly. 2)Identify the interface names and associated IP addresses. On racnode-1, #/sbin/ifconfig eth0 Link encap:Ethernet HWaddr 00:16:76:B0:46:7D inet addr:192.168.1.91 Bcast:192.168.15.255 Mask:255.255.240.0 inet6 addr: fe80::216:76ff:feb0:467d/64 Scope:Link UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 RX packets:96114 errors:0 dropped:0 overruns:0 frame:0 TX packets:1769 errors:0 dropped:0 overruns:0 carrier:0 collisions:0 txqueuelen:1000 RX bytes:7...

An Oracle RAC database is logically or physically shared everything database. All datafiles, control files, PFILEs, and redo log files in Oracle RAC environments must reside on shared disks. This is so that all of the cluster database instances can access them. IN that shared disk you can use the following file storage options for Oracle RAC database. 1)ASM: Which stands for Automatic Storage Management. And oracle recommends ASM. 2)Oracle Cluster File System (OCFS): OCFS is available for Linux and Windows platforms, or a third-party cluster file system that is certified for Oracle RAC. 3)A network file system: This is not supported on AIX, POWER, or on IBM zSeries-based Linux. 4)Raw devices In this post I will show how to configure RAW device to install oracle RAC. Before discussing it is good to know the difference between single instance database and RAC instance database. Oracle RAC databases differ architecturally from Oracle RAC single-instance Oracle databases in that each Or...