Swiss IT Pro SQL Server 2005 High Availability Options Agenda: - Availability Options/Comparison - High Availability Demo 08 August :45-20:00

Transcription

1 Swiss IT Pro Agenda: SQL Server 2005 High Availability Options - Availability Options/Comparison - High Availability Demo 08 August :45-20:00

2 SQL Server 2005 High Availability Options Charley Hanania 08 August

3 General Overview High Availability - Definition What s s new for H/A in SQL 2005 H/A Types H/A Comparison 5 nines... Something to think about Questions

4 What we will cover SQL Server Clustering Log Shipping Replication Database Mirroring

5 What we won t t cover Online Index rebuilds Table / Index Partitioning Data Centre Server Disk / Network Level H/A (RAID, NLB etc) SAN mirroring, Snapshots etc GEO Clusters Show interest, and we can present on these in the future (feedback forms)

6 High Availability - Definition Minimise the risk to the organisation of H/W and S/W failures Try to minimise the downtime (perceived downtime) Each H/A solution caters for different risks No one solution covers all bases Combining solutions may be best approach Careful planning/costing is advisable Changes may be needed in your application True H/A incorporates availability and performance models on all levels, business process, H/W, Application, N/W and service (employees)

7 What's new for H/A SQL 2000 gave us: Clustering : multiple nodes Log Shipping : multiple standby Replication Transactional Read only Updateable Subscriber

8 What's new for H/A SQL Server 2005 has now added Scriptable clustering installation A better log shipping model Point to point (peer to peer) replication Database mirroring Database snapshots (scalability) More cluster-aware SQL Services

9 Failover Clustering Eight nodes ~20-second failover Clustered Database Zero committed work lost More SQL services supported

10 Implementing Failover Clustering Heartbeat Network Private Network Shared Disk Array Virtual Server Clients Clustered Servers Effective but expensive

11 Log Shipping Multiple Copies No distance limits Trans scope maintained Manual Failover & reconfig

12 Replication Provides hot standby Single table to entire database No distance limits Some committed data loss No conflict detection

13 Fault Tolerance with Peer-to to-peer Los Angeles Zurich Sydney

14 Load Balancing with Peer-to to-peer Key Replication Read Write Read / Write Load Balancing Application Server Read-Only Load Balancing Application Server

15 Database Mirroring Less than three seconds Transparent client redirect Zero committed work lost Maximum one mirror per DB

16 Database Mirroring Concepts Principal: : The copy of the database that the applications connect to. The server that hosts it is known as the principal server. Mirror: : The copy of the principal database. always in a restoring state; not accessible to the applications. The server that hosts the mirror database is known as the mirror server. Witness: : Optional SQL instance. Separate from the principal and mirror instances. When used in synchronous mode, provides automatic failover.

17 Database Mirroring Concepts Send Queue: : Located at the Principle Used if the log records can t t be sent at the rate at which they are generated. It exists entirely in the transaction log. Redo Queue: : Located at the mirror Used if the log records can t t be applied at the rate at which they are received. Does not use extra storage or memory. Exists entirely in the transaction log of the mirror. It is the part of the hardened log that remains to be applied to the mirror database to roll it forward.

18 Database Mirroring Concepts Endpoint: : SQL Server object that enables SQL Server to communicate over the network. It encapsulates a transport protocol and a port number. Failover: : When the principal database (or the server hosting it) fails

19 Mirroring with Failover (Process) Principal Server Clients Witness Server Mirror Server

20 Mirroring with Failover (Process) Mirror Server Clients Witness Server Principal Server

21 Mirroring with Failover (Process) Mirror Server Clients Witness Server Principal Server

22 Comparison of High Availability Options Hot Standby Warm Standby Feature Database Mirroring Failover Clustering Peer-to- Peer Transactional Replication Log Shipping Data Loss No data loss option No data loss Some Data Loss possible Some data loss possible Some data loss possible Automatic Failover Transparent to Client Yes Yes Optional No No Yes, Auto- Redirect Yes, Reconnect to same IP Optional No, NLB helps No, NLB helps Downtime < 3 Seconds 20 Sec + DB Recovery None Seconds Seconds + DB Recovery Standby Read Access Continuously accessible Snapshot No Continuously accessible Continuously accessible Intermittently accessible

23 Comparison of High Availability Options Feature Database Mirroring Hot Standby Failover Clustering Peer-to-Peer Replication Warm Standby Transactional Replication Log Shipping Data Granularity Database Only All System and User Databases Table or View Table or View Database Only Masks Disk Failure Yes No, Shared Disk Yes Yes Yes Special Hardware Needed No, Dup. system needed Specialized Hardware from Cluster HCL No, Dup. system needed No, Dup. system needed No, Dup. system needed Complexity Some More More More More

24 5 nines Measured Annually Measured in 9 s 9 s (%) 99% = 3 days, 15 hrs & 40 minutes 99.9% = 8 hrs & 46 minutes 99.99% = 52 mins & 30 seconds % (5 nines!) = 5 mins & 15 seconds

25 SQL HA Resources SQL Server High Availability Site highavailability/default.mspx SQL Server Mission Critical High Availability nol/sql/themes/high-availability.mspx

26 Thank you