1. The response time for a transaction
2. The response time for a complete scenario
3. Finding out average response time
4. 90th % response time.

  <add key="LoggerConnectionString" value="Data Source=<<servername>>;Initial Catalog=&quot;<<DBName>>&quot;;User ID=<<UserID>>;Password=<<Password>>"/>  
  <add key="TableName" value="DataLog"/>
  <add key="ExceptionLogTable" value="ExceptionLog"/>
    <add key="TimeforExecutionmin" value="5"/>

</appSettings>

The following are the pre-requisites for performing Re-intialization with LSN

1. Distributor Server: It is the server that contains the distribution database and stores meta data, history data and transactions

2. Publisher Server: It is the server that makes data available for replication for subscribers.

3. Subscriber: It is the server that receives replicated data. we will have two subscribers in Failover. (i.e. Old subscriber and New Subscriber)

a. Old Subscriber: Server which is in failed state/Disaster state

b. New Subscriber: Server to which failover will be performed using LSN.

4. Publisher DB: It is the source of data to be replicated on the publisher server.

5. Subscriber DB: It is the destination database residing on subscriber server and receives replicated data.

6. Publication: Its refers to publication name property of publisher.

Steps for Performing Re-initialization with LSN: 

1. Finding the LSN number from the publisher. 

select @Query = '
 SELECT * FROM '+@subscriber_db+'.dbo.MSreplication_subscriptions
 WHERE publisher = '''+@publisher+
 ''' AND publisher_db = '''+@publisher_db+
 ''' AND publication = '''+@publication+''';'

2. Validate the LSN with distributor. 

SELECT @Query = '
 IF EXISTS(SELECT *
 FROM MSpublications p
 JOIN master..sysservers srv
 ON srv.srvid = p.publisher_id
 JOIN MSpublisher_databases d
 ON d.publisher_id = p.publisher_id
 JOIN MSrepl_transactions trans
 ON trans.publisher_database_id = d.id
 
 WHERE p.publication = '''+ $(publication) +'''
 AND p.publisher_db = '''+ $(publisher_db) +'''
 AND srv.srvname = '''+ $(publisher) +'''
 AND xact_seqno = '+ $(LSN) +'
 AND '+ $(LSN) +' > p.min_autonosync_lsn)
 BEGIN
 PRINT ''The LSN: '+ $(LSN) +' is correct''
 END
 ELSE
 BEGIN
 PRINT ''The LSN: '+ $(LSN) +' is wrong''
 END 
 
 '

3. Add subscription for the new subscriber on the publisher.

select @Query = '
 EXEC sp_addsubscription
 @publication = N'''+$(publication)+''',
 @subscriber = N'''+$(subscriber)+''', 
 @destination_db = N'''+$(subscriber_db)+''', 
 @subscription_type = N'''+$(subscription_type)+''', 
 @sync_type = N''initialize from LSN'', 
 @article = N''all'', 
 @update_mode = N''read only'', 
 @subscriber_type = 0,
 @subscriptionlsn = '+$(LSN)+';
 '

4. Adding subscription agent at the new subscriber

a. For Pull based replication

select @Query = '
 EXEC sp_addpullsubscription
 @publisher = N''' + $(publisher) + ''',
 @publication = N''' + $(publication) + ''',
 @publisher_db = N''' + $(publisher_db) + ''',
 @independent_agent = N''True'',
 @subscription_type = N''pull'',
 @description = N'' '',
 @update_mode = N''read only'',
 @immediate_sync = 0;
 
 EXEC sp_addpullsubscription_agent
 @publisher = N''' + $(publisher) + ''',
 @publisher_db = N''' + $(publisher_db) + ''',
 @publication = N''' + $(publication) + ''',
 @distributor = N''' + $(distributor) + ''',
 @frequency_type = 4,
 @frequency_interval = 1,
 @frequency_relative_interval = 0,
 @frequency_recurrence_factor = 0,
 @frequency_subday = 4,
 @frequency_subday_interval = 15,
 @active_start_time_of_day = 0,
 @active_end_time_of_day = 235959,
 @active_end_date = 99991231
 '

b. For Push based replication

select @Query = '
 EXEC sp_addpushsubscription_agent 
 @publication = N''' + $(publication) + ''', 
 @subscriber = N''' + $(subscriber) + ''', 
 @subscriber_db = N''' + $(subscriber_db) + ''', 
 @job_login = NULL, 
 @job_password = NULL, 
 @subscriber_security_mode = 1, 
 @frequency_type = 4,
 @frequency_interval = 1,
 @frequency_relative_interval = 0,
 @frequency_recurrence_factor = 0,
 @frequency_subday = 4,
 @frequency_subday_interval = 15,
 @active_start_time_of_day = 0,
 @active_end_time_of_day = 235959,
 @active_end_date = 99991231,
 @dts_package_location = N''Distributor'';
 ' 

5. Drop old subscriptions

select @Query = '
 EXEC sp_dropsubscription
 @publication = N''' + $(publication)+''', 
 @subscriber = N''' + $(subscriber)+''', 
 @destination_db = N''' + $(subscriber_db)+''', 
 @article = N''all'';
 '

1. Installation of Windows Server edition (2008 R2 or higher), SQL Server 2012, Windows Cluster + KB for quorum voting configuration, SQL Light Speed and DFS.
2. The primary and the secondaries on the primary datacenter and disaster recovery datacenter should be part of the windows failover cluster configuration.

Note: While the availability group appears as a resource in the WSFC, you should not attempt to manage it with Failover Cluster Manager or WSFC-scoped interfaces. Instead, manage the availability group within the context of the SQL Server instance via SQL Server Management Studio, Transact-SQL, or Windows PowerShell. For more information about why you should not use Failover Cluster Manager or other WSFC-scoped interfaces, see the blog post DO NOT use Windows Failover Cluster Manager to perform Availability Group Failover.     The AlwaysOn Dashboard is a recommended way to quickly view the health of a specific availability group. In it you can see the location of the primary instance, the failover mode of the replicas, the synchronization state of the replicas, and the failover readiness of the various replicas. You can also access the AlwaysOn Health Events Extended Events session data directly from the dashboard in order to view recent availability group activity, state changes, and events.    [Note: In order to understand more about Always on availability group, please have a read through of the white paper https://download.microsoft.com/download/D/2/0/D20E1C5F-72EA-4505-9F26-FEF9550EFD44/HomeDepot%20BCDR%20Whitepaper.docx]

In order to create replication for a database, create a new publication as shown in the figure.

1. Create publication on the publisher server.
2. Create subscription on either subscriber (in case of pull based subscription) or on the publisher ( in case of push based subscription).

1. Assume machine on which log shipping is performed as primary.

    PRIMARY = //MACHINE-NAME/ (or) //IP-ADDRESS/

    PRIMARY = SECONDARY but it can also be different.

2. Create a database => AdventureWorks on PRIMARY

   use AdventureWorks

   create table employee ( name varchar(20), age int);

   insert into employee values ('variable', 20)

   select * from employee

3. Create database => Adv1 on Secondary.

   Logshipping has to be done from Adventureworks to Adv1.

   Note: Log shipping can only be applied at the database level.

4. Setting recovery model

5. Setting the transaction log shipping

6. Setting primary server setting

For testing purpose set the scheduled time or 1 min and  in case of actual scenario leave it to default 15 min.

7. Adding secondary server

8. Secondary server = Primary server in our scenario

9. Restoring in secondary

Once jobs are running properly we have to perform breaking of logshipping.

Again go to properties of the database in PRIMARY SERVER. In Transaction Log shipping uncheck the check box which states enable transaction log shipping. This will disconnect the server. Once disconnected, the new database on the secondary will show restoring.

For bringing Adv1 online use the following command:

RESTORE DATABASE [Adv1] WITH RECOVERY

 Note: To test log shipping - insert a record in AdventureWorks just before breaking log shipping step and wait till the jobs complete. Once the jobs complete and we break log shipping the changes will get reflected in Adv1.