mylearning4oracle

 While I was working with oracle 11G cluster ware I used to come across a term called cluster health check monitor which actually helps us to analyze the cluster ware statistics. However this feature is optional as it used to consume more CPU and it is integral part of oracle database 11g where the data is maintained in Berkeley database. From Oracle 12.1.0.2, MGMTDB is a mandatory database installed by Oracle itself. The MGMTDB is a built-in database to store Grid Infrastructure Management Repository (GIMR). This repository enables such features as Cluster Health Monitor(aka CHM/OS, ora.crf), Oracle Database QoS Management, and Rapid Home Provisioning, and provides a historical metric repository that helps in  viewing of past performance and diagnosis of issues. Management Repository is a single instance database that's managed by Oracle Clusterware in 12c. The database will be automatically failed over to other node in case of node evictions. In 12.2, MGMTLSNR also listens o...

 This blogs explains a simple process to migrate your non cdb database to pdb database after 12 upgrade  We have different methods to perform the migration Export/import  DBMS_PDB GG replication  shutdown the database  start the database in read only mode  Now we need to create a metadata xml file using DBMS_PDB package BEGIN   DBMS_PDB.DESCRIBE(pdb_descr_file =>'/u01/app/oracle/backup/ora12c.xml'); END; /       4. shutdown the non-cdb database  and login to CDB database as sys user       5. Let us assume we don't have CDB database , if so we need to create CDB database       6. use DBCA -silent installation to create the CDB database        export ORACLE_SID=CDB sqlplus / as sysdba CREATE PLUGGABLE DATABASE PDBORCL USING '/u01/app/oracle/backup/ora12c.xml'   COPY   FILE_NAME_CONVERT = ('/u01/app/oracle/oradata/orcl/', '/u01/app/oracle/oradata/cdb/pdborcl/...

 This blog explains the basic steps which we need to follow to upgrade 11g database to 12c database  and preferably moving to PDB databases I have tried to read oracle MOS standard document ( How to Download and Run Oracle's Database Pre-Upgrade Utility (Doc ID 884522.1) )   which actually directs to different links explaining upgrade steps. But my intention is just to keep it simple to everyone when they were about to jumpstart the upgrade activity. We can follow couple of methods to perform the upgrade activity  Manual Method DBUA tool I prefer to go with manual method because automated method will always makes our life difficult when we struck during the upgrade process. But this have been fixed with 18c and 19c upgrades. Supported Upgrade Paths: =================  Destination                Source ===========                ====== 12c Release 1 (12.1.0.2)   10.2.0....

TDE stands for Transparent Data Encryption.TDE provides an additional layer of security by encrypting sensitive data and protecting it from unauthorized access. Some of the features: Encryption Types: Column level,tablespace level  Transparent Encryption and Decryption: Key Management: TDE uses a master encryption key to encrypt and decrypt the data using oracle wallet  Database-Level Encryption: TDE encrypts data at rest Compliance and Security:PCI(payment card Industry), HIPAA column level: ===========  -- Create the table with the column to be encrypted CREATE TABLE customer_data (   customer_id NUMBER,   credit_card_number VARCHAR2(16),   -- other columns ); -- Encrypt the 'credit_card_number' column BEGIN   DBMS_CRYPTO.ENCRYPT(     src => DBMS_CRYPTO.HASH_SH1,     key => 'encryption_key',     typ => DBMS_CRYPTO.ENCRYPT_AES256   );   DBMS_CRYPTO.ENCRYPT(     typ => DBMS_CRYPTO.ENCRYPT_AE...

session: This specifies that when the failover occurs, TAF should create session and perform no other action select: This specifies that when the failover occurs, TAF should create session and restart any select statements that were running at the time of the failover, only rows that were not previously returned will be returned to the user none: Do not perform a TAF failover Method This attribute determines when the session is created Basic : This establishes the session at the time of the failover Preconnect : when the initial connection to the database is made, this creates the failover session using Oracle Net alias designed by the backup attribute Retries This attribute specifies the number of times Oracle Net will go back to the address_list and attempt to connect to the surviving instances. Delay This attribute specifies the number of seconds to wait between each retry SATYA= (DESCRIPTION =    (ADDRESS_LIST =       (LOAD_BALANCE = YES)    ...

 Data guard is a feature of Oracle High availability . We have 2 types of dataguard  1-> logical standby  2- physical Standby  in this section I will discuss about physical standby  Architecture when a user process connects to the primary server it will perform DML operations as part of this the modified information is recorded in the log buffer. From log buffer data will be updated in to ORL(online redo logs ) using LGWR as redo entries.  The updated information / redo entries are read by the LNS(log network service) from redo buffer and passes through oracle net service and at the other side RFS process receives the redo data and applies on the SRL LNS Supports 2 types of transfer modes  Synchronous and Asynchronous transmission  In synchronous user commits a transaction creates a redo in redo buffer of SGA and it is being updated to ORL and waits for the confirmation from LNS as it reads the same data from redo and transmits to RFS to SRL ...

 Exadata: Oracle Exadata is a part of Oracle Engineered Family  Oracle Exadata Database Machine  is engineered to be the highest performing and most available platform for running  Oracle Database . It is a combination of Oracle Compute nodes and Oracle Storage nodes  A typical Exadata machine contains  -> Compute nodes (3,4,8) -> Storage nodes called as cell servers (14 cells with each cell containing 12 physical disks ) -> 2 infi band switches(for intra node communication) -> 1 cisco switch  -> 1 spine switch to group one or more  exadata machines -> each cell contains 4 flash cells with 6.5 TB (6.5 * 4 = 27 TB approx) Storage server runs on OLE6/7 installed with cell software to manage the cells  Some Important Points : ==============  ASM disk group will be created on grid disk -> cell -> LUN -> physical disks asm_diskstring  /o/cell ip/grid disk How to manage Exadata: =============== cellcli -> use...