AlwaysOn In SQL Server 2012 Fadi Abdulwahab – SharePoint Administrator - 4/2013

Terminologies  High Availability (Planned and Unplanned)  Disaster Recovery  Recovery Time Objective (RTO)  Recovery Point Objective (RPO)  Budget

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

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

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

Log Shipping

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

Replication

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

Mirroring

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)

SQL Cluster

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)

AlwaysOn

 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

 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

 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)

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

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