The AlwaysOn Availability Groups feature is a high-availability and disaster-recovery solution that provides an enterprise-level alternative to database mirroring. Introduced in SQL Server 2012, AlwaysOn Availability Groups maximizes the availability of a set of user databases for an enterprise

1. AlwaysOn
In SQL Server 2012
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2. Terminologies
 High Availability (Planned and Unplanned)
 Disaster Recovery
 Recovery Time Objective (RTO)
 Recovery Point Objective (RPO)
 Budget

3. Solutions in SQL Server
 Backup and Restore
 Log Shipping
 Replication
 Mirroring
 SQL Cluster
 AlwaysOn
 Mix and Third parties

4. Backup and Restore
 Can lose data
 Inexpensive Solution for DR
 No HA

5. Log Shipping
 HA , DR
 No Automatic Failover but automate the process of backup and restore
 Database Level
 Inexpensive solution

6. Log Shipping

7. Replication
 Database , Object level
 No automatic failover
 Can use as Load balance
 HA , DR

8. Replication

9. Mirroring
 HA , DR
 Automatic failover (need witness server – optional)
 Read-only database for secondary

10. Mirroring

11. SQL Cluster
 HA
 Expensive solution ( HD , License ,..)
 Server level
 Include two nodes or more
 Required SAN Storage
 A/P , A/A ,A/A/P,…
 Need DR (Log shipping , Backup and Restore,..)
 No Load Balance ( Use Transactional Replication)

12. SQL Cluster

13. AlwaysOn
 New Feature in SQL Server 2012
 Can have 5 replicas (one Primary and four secondary servers)
 HA , DR (enhancement for mirroring) and Read-only access
 Can be sync and async ( No acknowledgement ,minimize the transactions)
 No need for SAN storage (Not like SQL Cluster)
 Can deploy geographical
 Can use Secondary servers for backup and reporting access
 Automatic failover
 Types (Primary (R/W and send trans logs to secondary) and Secondary (R)

14. AlwaysOn

15.  Windows Cluster is required
 Interchangeable ( Transactions terminated)
 Failover can be ( Automatic , Manual and forced (possible data lose in
case of async) (by commands)
 Support T-SQL and PowerShell
 Diff Backup not supported for secondary
 Secondary use snapshots to avoid any blocking
 Support page repair
 Client can connect direct , Ava group and Read-only routing

16.  Read-only settings ( No , Read –intent only , Yes)
 Database should be :
 Not belong to any Ava. Group
 Enable R/W
 Enable Multi User mode
 Full Recovery
 Full backup
 Not used by mirroring

17.  Automatic Failover (up to 2) (Required Sync)
 Sync (Up to 3)
 Need DNS and Static IP ( can be DHCP)
 Configuration (Full (same path – need backup ) – Join (Already restored) – skip
(restore later
 When SQL user added to Primary the user must created in secondary (except if
use contained databases – New feature in SQL Server 2012)
 Backup Options
 Prefer (run on secondary except if primary not online)
 Secondary only (Not support diff backup)
 Primary only (support diff backup)
 Any replica (based on factors)

18. Demo
 Prerequisites ( Windows Cluster , 2 instances at least)
 Configuration (Enable , Create Ava. Group and backup)
 Add/Remove databases …
 Add/Remove Replica…
 Suspended and resume…
 Dashboard and DMVs for monitoring

19. Q&A
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