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
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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
What are Oracle Data Guard Protection Modes (redo transport rules) and how to configure them
A Data Guard configuration always runs in one of three data protection modes (also called as redo transport rules): Maximum Protection Maximum Availability Maximum Performance (default mode of operation) All three modes provide a high degree of data protection, but they differ in terms of the effect that each has on the availability and performance of the primary database. Data Guard Protection modes The supported redo transport configurations for the 3 Data Guard Protection Modes … [Read more...] about What are Oracle Data Guard Protection Modes (redo transport rules) and how to configure them
How to install and configure Oracle ASMLIB on Native Linux multipath mapper devices
The post describes the process about how to setup ASM & ASMLIB disks using Mapper Multipath disks. The process involves : Installing and configuring the ASMLIB software Creating partitions on multipath devices using kpartx Creating ASM disks on new partitions updating the configuration file /etc/sysconfig/oracleasm Creating ASM disk groups 1. Install and configure ASMLIB software Install the ASMLIB (on each node for RAC environments) and configure it. ASMLib consists of the … [Read more...] about How to install and configure Oracle ASMLIB on Native Linux multipath mapper devices
How to trace asmcmd command on UNIX/Linux
Question : The asmcmd command execution is slow. How to trace the asmcmd command? Answer: You are seeing some errors or slow performance issue with command execution on asmcmd. And you wish to get more information on the command execution. The exception raised from asmcmd is not very descriptive and more of generic errors are reported for different issues. Below are some of the ways in which you can trace the asmcmd command to troubleshoot the performance issues with the execution of the … [Read more...] about How to trace asmcmd command on UNIX/Linux