Data Replication in Distributed System Ehsan hessami

1. Data Replication in Distributed System Ehsan Hessami Islamic Azad University Of Qazvin

2. 2 kind Data Replication 1- Synchronous Replication 2PC(Two Phase Commit Protocol)Exp: 2- Asynchronous Replication 1- Primary Site Asynchronous 2- Peer-Peer Asynchronous

3. Primary Site Asynchronous Client Secondary Copy Primary Copy a D b c Update and Read only Translation Lazy Update Propagation Forward Update Transactions

4. Lazy master Framework Ownership ReplicaCopy 1- Primary Copy (denoted by capital Letters) Propagation 2- Secondary Copy (denoted by Lowercase Letters) Nodes 1- Master Save Primary Copy Refreshment 2- Slave Save Secondary Copy 3- Master Slave Save Primary & Secondary Copy Configuration Transactions 1- Update Transactions (T) Update Primary Copy 2- Refresh Transactions (RT) Update Secondary Copy 3- Queries (Q) Read Operation From Secondary Copy

5. Lazy master Framework Ownership Defines When The Update Transaction PrimaryCopy Must be Towards The Nodes Storing its SecondaryCopy Propagation Refreshment Type of Propagation 1-immediate Configuration 2- deferred

6. Lazy master Framework Ownership Defines When The Refresh Transaction Must be Start on SecondaryCopy. (immediate , deferred , wait). Propagation Refreshment The Couple Formed by The Propagation And The Trigger Mode 1-deferred-immediate Configuration 2- immediate-immediate 3- immediate-Wait

7. Lazy master Framework Ownership Defines The Component node of a Replication Schema . EXP 1 Master , n Slave Propagation Refreshment Configuration

8. System architecture Each Node (Slave & Master) Support DB And 3 Component : 1 – Replication Module 1-1 – Log Monitor 1-2 – Propagator 1-3 – Receiver 2 – Refresher 3 – Network interface

9. System architecture Log Monitor Propagator Receiver Refresher Used to extract changes to primary copy From History Log IF Find Write Operation , write into Input Log for Propagator

10. System architecture Log Monitor Propagator Receiver Refresher Each Record Have 4 Parameter (Primary ID , Field ID , Operation , New_Value). Propagator have 2 State : immediate , deferred

11. System architecture Log Monitor Propagator Receiver Refresher Each Message save in Reception Log Receiver Read from Reception Log IF we have 1 Master Node then Queue is 1 .

12. System architecture Log Monitor Propagator Receiver Refresher Checking the Queue for new incoming Record . Refresher is 3 kind : deferred-immediate , Immediate-immediate , Immediate_ wait

13. Connect and Disconnect Each Connect and Disconnect save in Historylog . ConnectTable Showing the nodes are Connect . Each node Have ConnectTable (Node_id,Replica_id , Status) . < “Connect” , Master_id , Slave_id , Replica_id > < “Disconnect” , Master_id , Slave_id , Replica_id >

14. Failure & Recovery Slave Failure : All the Connected Master Must Stop Sending Message To it Slave Recovery is Performed in 2 state : 1- < “Reconnect” , Master_id , Slave_id , Replica_id , Message_id > 2 – Searching in the Reception Log for all messages received from Master_id but not yet Processed by the Refresher .

15. Failure & Recovery Master Failure : The Slave Receiver a Fail Record : < “Fail” , Master_id > Master Recovery : < “Reconnect” , Master_id , Slave_id , Replica_id , Message_id > * . Message_id is null