MAA Architecture and High Availability

MAA Architecture and High Availability

Oracle 12.2 RDBMS with the configuration with ASM, Data-Guard incorporates clustering technology for improved availability for both unplanned outages and planned maintenance. 

Oracle RAC or Oracle RAC One Node for HA within a data center by providing automatic failover should there be an unrecoverable outage of a database instance or a complete failure of the server on which it runs.

Oracle RAC also delivers substantial benefits for eliminating many types of planned downtime by performing maintenance in a rolling manner across Oracle RAC nodes. 

Oracle RAC

Oracle RAC improves application availability within a data center should there be an outage of a database instance or of the server on which it runs. Server failover with Oracle RAC is instantaneous. 

There are two components: Oracle Database instances and the Oracle Database itself.

·         x`A database instance is defined as a set of server processes and memory structures running on a single node (or server) which makes a particular database available to clients.

·         The database is a particular set of shared files (data files, index files, control files, and initialization files) that reside on persistent storage, and together can be opened and used to read and write data.

·         Oracle RAC uses an active-active architecture that enables multiple database instances, each running on different nodes, to simultaneously read and write to the same database.

Advantages of active-active Instance cluster in Oracle RAC

·         Improved HA within the cluster

·         Scalability

·         Reliability

·         HA during planned maintenance like the rolling patch

Oracle One-Node RAC

Oracle RAC One Node provides an option to Oracle RAC when server HA is a requirement, but scalability and instant failover are not.

Oracle Data Guard and ADG

Oracle Active Data Guard maintains one or more synchronized physical replicas (standby databases) at a remote location that are used to eliminate a single point of failure for a production database (the primary database). 

Here in BSP, Oracle Database hosting Oracle Flexcube is been configured with ADG to Report Database and DG in Standby Database (remote location).

Rest of Application database Databases are configured with a single node Standby Database (DG) in the remote location.

RTP and RPO

Here we eliminate single point of failure and provide a higher level of data protection and HA from all types of unplanned outages including data corruption, database failures, and site failures.

The existence of a replicated copy also provides substantial advantages for reducing downtime during periods of planned maintenance.

RTO is reduced to seconds or minutes with RPO of zero or near zero depending upon configuration.

Features during Backup/ Restore	Details	With ZDLRA Recovery Appliance	Without ZDLRA Recovery Appliance
Zero or near-zero data loss potential.	Site failure, Database Failure	Delta push after full backup forever based on backup policies Real-time transactions copied over for continuous data protection
Oracle Active Data Guard/ Standby database		Zero data loss in case of Database Failure 1 sec RPO	Near-Zero data loss
Clone to non-prod database	Preparing a copy of the Production database.	Quickly and easily (using OEM) clone full production databases to non-production environments
Backup offload		No overhead while taking database Backup	Overhead during the backup cycle,  Backup to schedule in both Primary and Standby databases.
Validation for Data-corruption	Data corruption in Storage DIsks	Detect errors on Backup while taking instead at during restore backup	Manually Execution of dbverify or Analyze commands, Recreate objects from Standby or from Backup in case of physical corruption. RMAN Crosscheck Backup, RMAN Restore Validate V$DATABASE_BLOCK_CORRUPTION;  RMAN> RECOVER BLOCK DATAFILE xxx BLOCK yyy; Data Recovery Advisor recommend commands to perform restore and recovery procedures for Corruption Method Corrupted Block Block Media Recover Database/ datafile The point in Time Recovery Flashback the entire database
Automatic block repair	Physical block corruption; corruption can be caused by a faulty disk or disk controller, an errant bit-flip on a disk, or a bug in the operating system, storage area network (SAN), or storage system	·         Ingest of Backupsets & Redo Logs ·         Indexing Backupsets into Delta Store ·         Replicating Backupsets & Redo Logs ·         Optimization of the Delta Store ·         Timer Based Validation ·         Validation during Restore ·         Mirror Sync Validation	It can be achieved using Oracle DG, Data Recovery Advisor, Oracle Flashback, Oracle RMAN. Configuration of the DB_BLOCK_CHECKING=FULL, DB_BLOCK_CHECKSUM=FULL, and DB_LOST_WRITE_PROTECT=TYPICAL parameters on the Data Guard primary and standby databases. ( add overhead in the database during write operations) Use Active Data Guard to enable Automatic Block Repair ( applicable for FCUBS database from Report Database)
TDE Data Encryption	Tablespace or Table column Encryption	Support functionality during backup/ restore	Support functionality to central Backup location and Tape drives.
Rapid Database Backup Restoration	Online Database Backup using RMAN as per policy defined Database Restore using RMAN	With RA Appliance, Database backup at any point of time can be restored in original or in the second database Unified OEM console for tracking backup and restore/ recovery jobs Able to generate chargeback reports against each database.	Using Oracle Secure Backup and SL150 Tape Library. Manually initiated or through OEM using OSB plugin
Backup Restoration	Database restore during failure	Creates virtual Full Backup of database every-time → Reduces restore time. Use of Backup Flash Area (NvME storage) for fast backup. Use of Delta Push using RMAN during backup;  Re-assemble delta push, validate the physical Full backup during the restore Restore database backup at any N-day and time.	Uses RFS and MRP processes for REDO block shipping and applying changes. Use tagged backup during restore, Catalog TAPE before-hand manually or through OSB.
Ownership of taking and restoring Backup	Responsibility of taking backup	Single OEM console, Application or Stream-based policies;	Multiple back-ups between DBA's, storage admin and Backup Admin Manually attached policies at the time of backup provisioning.
Backup Protection	Protection against deletion, manual (ad-hoc backup execution)	Policy to protect deletion of backup manually or through RMAN	No protection

Handling Outages

Type	Event	Downtime	Data Loss Potential
Unplanned	Database instance failure	Seconds	Zero
Unplanned	Recoverable server failure	Seconds	Zero
Unplanned	Data corruptions, unrecoverable server failure, database failures or site failures	Zero to minutes (instead of hours to days)	Near-zero if using ASYNC (instead of since the last backup) Zero if using Data Guard synchronous transport (instead of since the last backup)
Planned	Online File Move, Online Reorganization, and Redefinition, Online Patching	Zero	Zero
Planned	Hardware or operating system maintenance and database patches that cannot be done online	Zero	Zero
Planned	Database upgrades: patch sets and full database releases	Seconds (instead of minutes to hours)	Zero
Planned	Platform migrations	Seconds (instead of hours to a day)	Zero
Planned	Application upgrades that modify back-end database objects	Hours to days	Zero

Data protection offering

Type	Capability	Physical Block Corruption	Logical Block Corruption
Type	Capability	Physical Block Corruption	Logical Block Corruption
Manual	Dbverify, Analyze commands	Physical block checks	Logical checks for intra-block and inter-object consistency
Manual	RMAN	Physical block checks during backup and restore	Intra-block logical checks
Runtime	Oracle Active Data Guard	Physical block checking at standby Strong isolation between primary and standby eliminates the single point of failure Automatic repair of physical corruptions Automatic database failover	Detect lost write corruption, auto shutdown, and failover Intra-block logical checks at standby
Runtime	Database	In-memory block and redo checksum	In-memory Intra block logical checks
Runtime	ASM	Automatic corruption detection and repair
Runtime	Recovery Appliance	HARD checks on write	HARD checks on write
Background	Recovery Appliance	Automatic Hard Disk Scrub and Repair	n/a
Background	Recovery Appliance	Complete backup validation including control file, data file backups and REDO	n/a