====== Lesson 1: Introduction to High Availability ======
===== Factors Affecting Availability =====
  * Software failures
  * Hardware component failures
  * Network failure
  * Power failure and natual disaster
        
===== Considerations for Optimizing Database Availablity =====
  * Hardware component redundancy
  * Network redundancy
  * RAID
  * Server and database redundancy      

====== Lesson 2: Implementing Server Clustering ======
===== What Is Server Clustering? =====
  * Virtual Server
    * Appears on the network as a normal server
  * Editions
    * Enterprise Edition
    * Developer Edition
    * Standard Edition
                       
===== Considerations for Cluster Preparation =====
Check configuration and compatibility of:
  * Hardware
  * Windows cluster configuration
  * Shared disk
      
===== How to Install SQL Server in a Cluster =====
  * Virtual Server
    * Specify a virtual server name in SQL Server Setup
  * Instances
    * Only one instance of SQL Server in each resource group           

====== Lesson 3: Implementing Database Mirroring ======
===== What Is Database Mirroring? =====
  * Alternative to failover clustering
  * Mirror Server
    * Provides a hot standby
  * Witness Server
    * Monitors the primary and mirror database servers
  * Client redirection
    * Automatic client redirection
                         
===== Options for Database Mirroring Configuration =====
^  Mode  ^  Automatic Failover  ^  Full Protection from Data Loss  ^
^ High Availability |  O  |  O  |
^ High Protection   |  X  |  O  |
^ High Performance  |  X  |  X  |

===== What Are Database Mirroring Endpoints? =====
  * TCP endpoint that enables network communication between servers <code sql>
CREATE ENDPOINT endpointName
    STATE=STARTED
    AS TCP ( LISTENER_PORT = listenerPortList )
    FOR DATABASE_MIRRORING
    (
        [ AUTHENTICATION = WINDOWS [ authorizationMethod ]
        ]
        [ [,] ENCRYPTION = REQUIRED
                [ ALGORITHM { algorithm } ]
        ]
        [,] ROLE = role
    )
</code>
  
===== How to Prepare Servers for Database Mirroring =====
  - Create mirroring endpoints and logins
  - Set recovery model to FULL
  - Back up database and restore on mirror server
  - Copy server-level resources

===== How to Establish a Mirror Session =====
  - Set the pricipal server on the mirror server
  - Set the server on the principal server
  - Change the session mode from High Protection
    * Add a witness server for High Availability mode
    * Set partner safety off for High Performance mode
        
===== How to Handle Failover =====
  * Automatic failover
    * Mirror and witness form quorum
    * Role changes automatically
  * Manual failover <code sql>
ALTER DATABASE AWData
SET PARTNER FAILOVER
</code>                
  * Forced service <code sql>
ALTER DATABASE AWData SET PARTNER
FORCE_SERVICE_ALLOW_DATA_LOSS
</code>
  
====== Lesson 4: Implementing Log Shipping ======
===== What Is Log Shipping? =====
  * A high-availability technique that applies log backups to a standby server
  
===== How to Implement Log Shipping =====
  * Implement log shipping in either:
    * SQL Server Management Studio
    * Transact-SQL <code sql>
sp_add_log_shipping_primary_database
@database = N'AdventureWorks'
,@backup_directory = N'c:\lsbackup'
,@backup_share = N'\\tribeca\lsbackup'
,@backup_job_name = N'LSBackup_AdventureWorks'
</code>

===== How to Switch Server Roles =====
  - Copy transaction log backups
  - Back up primary database with NORECOVERY <code sql>
BACKUP LOG AdventureWorks TO AWLogBackup
WITH NORECOVERY
</code>
  - Restore primary database on secondary server <code sql>
RESTORE LOG AdventureWorks FROM AWLogBackup
WITH RECOVERY
</code>
  - Disable log shipping jobs
  - Configure log shipping on new primary server

====== Lesson 5: Implementing Peer-ot-Peer Replication ======
===== Considerations for Using Peer-to-Peer Replication =====
  * Effects of transactions and cnoflicts
  * Improved performance and scalability
  * Control over network traffic
  * Suitability over intermittent network connections
        
===== Implementing Distributed Load Balancing =====
  * Update and read load balancing
  * Read load balancing
    
===== Implementing Distributed High Availability =====
  * Synchronizing nodes
  * Peer-to-peer replication topologies
  * Implementing a peer-to-peer replication topology