Here is a short note on ASM background processes and their purpose in managing Oracle ASM instances. Background ProcessDescription ASMBASM Background Process RBALASM Rebalance Master Process ARBnASM Rebalance Process DBWRDatabase Writer Process SMONSystem Monitor Process CKPTCheckpoint Process PSP0Process Spawner Process GMONASM Disk Group Monitor Process MARKMark AU for Resynchronization Coordinator Process VKTMVirtual Keeper of Time Process LGWRLog Writer Process … [Read more...] about ASM background processes in 11gR2
oracle
Understanding Oracle Background Processes
Oracle Background Processes The background processes of the Oracle instance manage memory structures, asynchronously perform I/O to write data to a file on a disk, and perform general maintenance tasks. An Oracle database system consists of an Oracle database and an Oracle instance. The database consists of a set of disk files that store user data and metadata, while the Oracle/database instance contains the set of Oracle Database background processes that operate on the stored data and the … [Read more...] about Understanding Oracle Background Processes
How to change the SCAN IP address (SCAN VIP resources) in 11gR2 Grid (CRS) environment
The IP addresses associated with the SCAN VIP resources are initially set when the SCAN resources are created. Any changes to the DNS entry for the SCAN are not automatically propagated to the clusterware and need to be done manually. This applies only to installations that are not using GNS. The information in this note can also be helpful in cases where SCAN was originally configured with just one address and is now being expanded to accommodate three IP addresses. Below is an example using … [Read more...] about How to change the SCAN IP address (SCAN VIP resources) in 11gR2 Grid (CRS) environment
Common Init.ora Parameters and Unix, Linux Kernel Parameters and Relationship Between Them
Its is important to know the most commonly used parameters in the pfile/spfile and their relationship with the kernel parameters to troubleshoot issues. The following table documents Unix and Linux kernel parameters that should be monitored and possibly increased after changes are made to the related init.ora parameter. Init.ora ParameterKernel Parameter db_block_buffersshmmax, shmall db_files (maxdatafiles)nfile, maxfiles large_pool_sizeshmmax, shmall log_buffershmmax, shmall … [Read more...] about Common Init.ora Parameters and Unix, Linux Kernel Parameters and Relationship Between Them
Oracle Database Environment Variables and Their Functions
Oracle Database Environment Variables Below are some of the most common environment variables used with Oracle Database and their descriptions: NLS_LANG: Specifies the language, territory, and character set of the client environment. The client character set specified by NLS_LANG must match the character set of the terminal or terminal emulator. ORA_NLS10: Specifies the directory where the language, territory, character set, and linguistic definition files are stored. ORA_TZFILE: Specifies … [Read more...] about Oracle Database Environment Variables and Their Functions
CentOS / RHEL 7 : How to set udev rules for ASM on multipath disks
Udev is the mechanism used to create and name /dev device nodes corresponding to the devices that are present in the system. Udev uses matching information provided by sysfs with rules provided by the user to dynamically add the required device nodes. The post describes how to set udev rules for ASM disks in a dm multipath environment. The multipath disk used as an example is /dev/mapper/multipathx. We will be setting the udev rule for the multipath disks to have ownership of … [Read more...] about CentOS / RHEL 7 : How to set udev rules for ASM on multipath disks
How to Configure Device File owner/group with udev rules
What is udev and udev rules Udev is the mechanism used to create and name /dev device nodes corresponding to the devices that are present in the system. Udev uses matching information provided by sysfs with rules provided by the user to dynamically add the required device nodes. There are no static files under /dev directory for devices, devices are created/removed dynamically by udev(or udevd) which is a daemon monitoring what devices are connected/disconnected on to the kernel, and run … [Read more...] about How to Configure Device File owner/group with udev rules
Oracle Solaris Cluster : Understanding quorum votes and quorum devices (How to avoid Failure Fencing and Amnesia)
Need for Quorum Voting A quorum device is a shared storage device. A quorum server is shared by two or more nodes to contribute votes that are used to establish a quorum. Clusters operate only when a quorum of votes is available. Describing Quorum Votes and Quorum Devices The cluster membership subsystem of the Oracle Solaris Cluster software framework operates on a voting system as follows: Each node is assigned exactly one vote. Certain devices can be identified as quorum devices and … [Read more...] about Oracle Solaris Cluster : Understanding quorum votes and quorum devices (How to avoid Failure Fencing and Amnesia)
How to relocate or move oracle database files using RMAN
The requirement here is to move or relocate the database files to some other location. So, there are 2 scenarios here, 1. Relocating all the database files - datafiles, online redo logs, and controlfiles ( This requires the database to be in mounted mode ) 2. Relocating Non-system datafiles - This can be relocated with minimal outage. The examples below use /data02/oradata as the new destination. You can use any destination you like, including new ASM disk groups. So For this example, we … [Read more...] about How to relocate or move oracle database files using RMAN
Oracle Database interview questions – Privileges And Roles
What is a Privilege? A privilege is the right to execute a particular type of SQL statement. It can allow a user to access database objects or execute stored programs that are owned by another user or to perform system level actions. There are two types of privileges: system privileges schema object privileges What are system privileges? The system privileges are not related to a certain object. They control the ability of a user to perform system level actions such as connecting to … [Read more...] about Oracle Database interview questions – Privileges And Roles