1. SQL Server 2008 R2 Implementing High Availability

2. High availability Challenge

3. SQL Server 2008 R2 High Availability Goals Hardware Failover Clustering Database Mirroring Replication Log Shipping

4. Goals for High Availability Second copy of our data Have Real time or Near Real time switch over Second copy – Updated Frequently Reduce workload – Automatic Switch over to the second database Less downtime for our users

5. Techniques available Hardware Failover clustering Database Mirroring Replication Log Shipping

6. Hardware Redundant Power supplies RAID Arrays Redundant CPU Power Redundant Network Cards SCSI/SAN Controllers Key is redundancy

7. SQL Server failover clustering Node A Node B H/W H/W Nodes Clients Active - Passive

8. SQL Server failover clustering Node A Node B H/W H/W Nodes A Nodes B Active - Active Clients

9. A SQL 1 SQL 2 D B SQL 7 SQL 3 SQL 8 SQL 4 C SQL 5 SQL 6

10. SQL 1 (Principal) SQL 2 (Mirror) A A (copy) Transaction B Clients SQL Native Client

12. Provides a fault-tolerant database

13. Cost effective as no specialized hardware is required

14. Straightforward setup and administration

15. Automatic or manual failover

16. SQL Server 2008 R2 does not require a database restart after manual failover

17. No shared components; two separate copies of data

19. Replication Transactional Merge Replication Snapshot Replication There is no built in type of Failover

20. A B C

21. Clients Tokyo New York New Delhi

22. Replication High performance ─ latency measured in seconds Minimal load on the server Cost effective as no specialized hardware is required Straightforward setup and administration Subscriber is accessible Used mainly for Scalability

23. SQL 1 SQL 2 A A (copy) Transaction Log Backup Transaction Log Backup B Clients

24. Log Shipping Not Real-time Less Resource Hungary on Servers Supports FILESTREAM Provides database redundancy Every some [Time] Filestream

25. Log Shipping Cost effective as no specializedhardware is required Straightforward setup andadministration Running read operationssuch as reports on asecondary server is permitted Users are disconnected when logrestore occurs

26. Log Shipping Can maintain multiple secondary servers Records history and status of backup/restore jobs May set up to raise alerts when jobs fail

28. Hardware

29. Failover Clustering

30. Database Mirroring

31. Replication