mylearning4oracle

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...

 LREG (Listener registration Process):dynamic listener registration This is introduced from oracle 12c onwards, previously the same job is done by the PMON process of the oracle database  Prior to oracle 12c , PMON used to register the database information  to the Listener process , infact it used to do  service_update, service_register, service_died.  In order to reduce the load on PMON LREG process will do the following actions  ->  Registers instance information with the listener -> if the LREG process got killed then automatically instance will go down -> It does  service_update, service_register, service_died. command to trace dynamic registration  alter system set events='immediate trace name listener_registration level 0';

In Oracle RAC we have 2 types of listeners  Remote Listener  Local Listener  Remote Listener always updated with scan IP and local listener with Local VIP of the instance. When ever user process makes a connection request to the scan listener it uses LBA(load Balance Advisory ) to redirect the connection to the  local listener of the least node of the cluster in Round Robin fashion. Oracle Load balancing is of 2 types  client side and server side  Client-side load balancing balances the connection requests across the listeners. With server-side load balancing server-side load balancing, the SCAN listener directs a connection request to the best instance currently providing the service by using the load balancing advisory. Note: In Oracle RAC the default  connection is dedicated connection , however we can specify shared connection during DBCA configuration