There could be a requirement from client to have custom device names such as /dev/asmdisk01 for an actual device with name /dev/sdb. Follow the steps outlined in this post to set custom device names using udev. In order to create customer name (/dev/asmdisk01p1) for /dev/sdb set udev rules as below: 1. Find UUID of device First, find the the UUID of the device with the scsi_id command as shown below. # /usr/lib/udev/scsi_id -g -u /dev/sdb 1IET_00020002 Save this UUID, as this ID … [Read more...] about How to set custom device names using udev in CentOS/RHEL 7
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Oracle database 12c : How to Drop Partition(s)
Dropping a Partition Dropping a partition will discard the rows stored in that partition as a DDL statement. This cannot be rolled back. It executes quickly and uses few system resources (Undo and Redo). You must be the owner of the table or have the DROP ANY TABLE privilege to drop a partition. You cannot drop a partition of a hash-partitioned table. You cannot drop a partition from a reference-partitioned table. If a drop partition is performed on a parent table, this operation cascades to … [Read more...] about Oracle database 12c : How to Drop Partition(s)
How to Drop/Truncate Multiple Partitions in Oracle 12C
The following are the partitioning related enhancements introduced in Oracle 12c: Online partition operations Reference partitioning enhancements Multi-partition maintenance operations Adding multiple partitions Truncating multiple partitions Merging multiple partitions Splitting into multiple partitions Dropping multiple partitions Dropping a Partition Dropping a partition will discard the rows stored in that partition as a DDL statement. This cannot be rolled back. It … [Read more...] about How to Drop/Truncate Multiple Partitions in Oracle 12C
How to Split a Partition Into Multiple Partitions in Oracle 12c
The following are the partitioning related enhancements introduced in Oracle 12c: Online partition operations Reference partitioning enhancements Multi-partition maintenance operations Adding multiple partitions Truncating multiple partitions Merging multiple partitions Splitting into multiple partitions Dropping multiple partitions Splitting Partition into multiple partitions You can split a partition into multiple partitions. In previous releases, you were able to split … [Read more...] about How to Split a Partition Into Multiple Partitions in Oracle 12c
How to Merge Multiple Partitions in Oracle 12c
The following are the partitioning related enhancements introduced in Oracle 12c: Online partition operations Reference partitioning enhancements Multi-partition maintenance operations Adding multiple partitions Truncating multiple partitions Merging multiple partitions Splitting into multiple partitions Dropping multiple partitions Merging multiple partitions In Oracle 11g, you can merge the content of two partitions only in single DDL. However, in Oracle 12c, you can merge … [Read more...] about How to Merge Multiple Partitions in Oracle 12c
How to recreate Control file in Oracle Database
What are control files? The control file is a binary file that defines the current state of the physical database. The control file is one of the core files at the heart of the Oracle database. Together, this means that the Oracle instance itself is the only means by which the contents of the control file should ever be modified. The DBA should only modify it indirectly by means of altering the database. Loss or corruption of the control file requires a database recovery. The control file is … [Read more...] about How to recreate Control file in Oracle Database
Managing Oracle Database Backup with RMAN (Examples included)
Installed with the database, Recovery Manager (RMAN) is an Oracle database client which performs backup and recovery tasks on your databases and automates the administration of your backup strategies. It greatly simplifies backing up, restoring, and recovering the database. The RMAN environment consists of the utilities and databases that play a role in backing up your data. At a minimum, the environment for RMAN must include the following: The target database. This is the database to be … [Read more...] about Managing Oracle Database Backup with RMAN (Examples included)
How to resize an OCFS2 filesystem on Linux
The post outlines the steps to resize an OCFS2 filesystem on Linux. The procedure should first be tested in test before being performed against a production environment. 1. Backup all data on the filesystem Repartitioning a disk/device is a destructive process that may result in complete loss of volume data. Backup the contents of the volume to be resized before proceeding. 2. Globally unmount the filesystem to be resized OCFS2 filesystem resize can only be performed with the filesystem … [Read more...] about How to resize an OCFS2 filesystem on Linux
How to set udev rule for setting the disk permission on ASM disks when using multipath on CentOS/RHEL 6
This note explains how to set udev rule for setting the disk permission on ASM disks in multipath on CentOS/RHEL 6.x. Follow the below steps if you are using multipath and want to set udev rule on multipath device. 1. Determine partitioned alias for target device # dmsetup ls |grep p1 datap1 (253, 4) ### you would see something similar to this 2. Edit /etc/udev/rules.d/12-dm-permissions.rules file to set the above device ownership as oracle:dba. # vi … [Read more...] about How to set udev rule for setting the disk permission on ASM disks when using multipath on CentOS/RHEL 6
Oracle Database Interview Questions : Redo Logs and Archiving
What is the Redo Log? Redo Logs consist of two or more pre-allocated files that store all changes made to the database as they occur. Every instance of an Oracle Database has associated online redo logs to protect the database in case of an instance failure. Redo log files are filled with redo records. A redo record also called a redo entry, is made up of a group of change vectors, each of which is a description of a change made to a single block in the database. Redo entries record data … [Read more...] about Oracle Database Interview Questions : Redo Logs and Archiving