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Database replication
- 1. Database Replication Orient Energy System
- 2. Data Replication Meaning • Copying data from a database from one server to another server. • All the users can share the same data without any inconsistency. • Replication can be executed via three types of networks: Storage Area Network (SAN), Local Area Network (LAN) or Wide Area Network (WAN). • Data replication can be divided into two Categories : 1-Synchronous replication 2-Asynchronous replication
- 3. Synchronous vs Asynchronous Synchronous replication • Synchronous replication creates copies of data in real time • Propagates every transaction • Creating connections for every transaction • Expensive but very reliable in the event of a disaster • Write data to primary storage and the replica simultaneously Asynchronous replication • Creates copies of data as per defined schedule • Propagates Multiple Transaction • Uses less network bandwidth and offers better performance • Less Expensive than Synchronous replication and More Data Lost chances • Write data to the primary storage first and then copy the data to the replica
- 4. Synchronous vs Asynchronous Creating replicas in real time Creating time delayed replicas
- 5. Types of Replication Master-Slave • One master server , others slave. • Write on master propagates to slaves. • Configure slave to take over as master if original master falls out. Multi-Master • All servers are master. • Write on any server , propagate to others. • Powerful and flexible solution but also very complex.
- 6. Advantages Of Replication • Availability • Has Reliability • Gives high Performance • Facilitates load reduction • Provide disconnected computing • Supports many users • Supports latest versions or advanced applications
- 7. Disadvantages of Replication • Require more Storage Space • Expensive • Complex Maintaining Data Consistency
- 8. Who use Data Replication? • Data Backup– Data replication is associated with data availability and disaster recovery (DR) if data lost or damage. • Additional Transactional Processing Systems – These facilitate real time reactions to transactional occurrences or changes. • Application Development Projects – Such projects demand immediate access to data to maximize business results. • Big Data Analytics – Analytics depends on data accessibility across teams of analysts working with the same data. • Data Synchronization – Data management projects, analytical data marts, mainframe environments and data warehouses can effectively leverage replication for data synchronization purposes.
- 9. How does Data Replication Implemented? Replication can be implemented using several different methods. Here are some of the ways you can utilize data replication. • Host-based replication. • Hypervisor-based replication. • Array-based replication. • Network-based replication.
- 10. • Host-based replication – Purpose built servers : For this type of data replication, application servers paired with software are used to create replicas/copies of data from one site to another. This replication is mostly file-based and asynchronous. • Hypervisor-based replication – Replicate entire VMs : This type of data replication is specifically designed to copy/replicate entire Virtual Machines (VMs) from one host server or host cluster to another. This ability of replicating entire VMs facilitates disaster recovery by easing fail over to the replicated copy of the primary system. • Array-based replication – Built-in Software Automatically Replicates Data : In this data replication type, built-in software is used in compatible storage arrays to automatically replicate data between them • Network-based replication – Supports any host platform : This type of data replication requires an additional switch or appliance between storage arrays and servers. Network-based replication can support any host platform and can work with any array.
- 11. Replication Schemes Full Replication – The most extreme case is replication of the whole database at every site in the distributed system. This will improve the availability of the system because the system can continue to operate as long as atleast one site is up. Advantages of full replication – • High Availability of Data. • Improves the performance for retrieval of global queries as the result can be obtained locally from any of the local site. • Faster execution of Queries. Disadvantages of full replication – • Concurrency is difficult to achieve in full replication. • Slow update process as a single update must be performed at different databases to keep the copies consistent.
- 12. Replication Schemes No Replication – The other case of replication involves having No replication – that is, each fragment is stored at only one site. Advantages of No replication – • The data can be easily recovered. • Concurrency can be achieved in no replication. Disadvantages of No replication – • Since multiple users are accessing the same server, it may slow down the execution of queries. • The data is not easily available as there is no replication.
- 13. Replication Schemes Partial Replication – In this type of replication some fragments of the database may be replicated whereas others may not. The number of copies of the fragment may range from one to the total number of sites in the distributed system. The description of replication of fragments is sometimes called the replication schema. Advantages of Partial replication – • The number of copies of the fragment depends upon the importance of data.