Till 12cR1 the Undo tablespace used to be shared or global across all the PDBs in a container. From 12cR2 onwards, the local Undo is introduced. When local undo is enabled, each container has its own undo tablespace for every instance in which it is open. When local undo is disabled, there is one undo tablespace for the entire CDB. The Undo mode, whether it’s local or shared, is the property of the entire CDB. Either all the PDBs are local undo mode or there’s shared undo for the entire CDB. … [Read more...] about Undo Modes in 12.2 Multitenant Databases – Local and Shared Modes
oracle 12c
How to Move OCR, Vote Disk File, ASM SPILE to new Diskgroup
The goal here is to move OCR, voting disk file and ASM spfile in a Grid Infrastructure with RAC cluster to a new ASM disk group. One example would be that you have created these components in the +DATA diskgroup and you wish to move the OCR, Vote File and ASM spfile to a NORMAL or HIGH redundant diskgroup. Basic steps to move to the new diskgroup are outlined below: Create New diskgroup(CRS) with suitable redundancy for OCR and Voting files. Ensure that the new diskgroup is mounted on all … [Read more...] about How to Move OCR, Vote Disk File, ASM SPILE to new Diskgroup
New Background Processes In Oracle Database 12c
The post provides information on new background processes introduced in 12c. Background ProcessDescription BWnnDatabase Writer Processes FENCFence Monitor Process IPC0IPC Service Background Process LDDnGlobal Enqueue Service Daemon Helper Slave LGnnLog Writer Worker LREGListener Registration Process OFSDOracle File Server Background Process RPOPInstant Recovery Repopulation Daemon SAnnSGA Allocator SCRBASM Disk Scrubbing Master Process SCRnASM Disk Scrubbing Slave … [Read more...] about New Background Processes In Oracle Database 12c
Understanding Oracle Database Automatic SGA Memory Tuning
In Oracle Database 10g, Automatic Shared Memory Management (ASMM) feature is introduced to automatically determine the size of Database buffer cache (default pool), Shared Pool, Large pool and Java pool (starting with 10gR2, the streams pool is included) by setting the parameter SGA_TARGET. This feature reduces the tasks like dynamically analyzing the database workload and redistribute memory across the SGA pools. Benefits of Automatic Shared Memory Management Automatic Shared Memory … [Read more...] about Understanding Oracle Database Automatic SGA Memory Tuning
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 create password file for Database on 12c ASM diskgroup
The compatible.asm disk group attribute must be set to 12.1 or higher for the disk group where the password is to be placed. Steps 1. Create the password file using the following command. Go to the asmcmd command prompt and run : $ asmcmd ASMCMD> pwcreate --dbuniquename [dbuniquename] [file_path] [sys-password] Here, The --dbuniquename string option identifies the database unique name associated with the password file. The file_path value identifies the location where the password … [Read more...] about How to create password file for Database on 12c ASM diskgroup