Disaster Recovery Using AlwaysON Availability Group – Scenario 2

Environment

Blog25_1-> Disaster Recovery scenario is as below,

  • PRIMARY DATA CENTRE goes down.
  • The databases on Server JBSERVER2 should be made online and have the application connect to Database Server JBSERVER2.
  • Failback Availability group back to JBSERVER1 when PRIMARY DATA CENTRE comes online.
  • The changes made by the Application on JBSERVER2\IN2014 should be discarded.

-> Checking the current AlwaysON setup in SQL Server Management Studio,

Blog26_2

-> The Database JB_DB contains a table named Table5, which we will use for testing.

USE [JB_DB]
GO
CREATE TABLE [dbo].[Table5](
[sno] [int] IDENTITY(1,1) NOT NULL,
[sname] [char](2000) NULL,
[sname1] [char](2000) NULL,
[sname2] [char](2000) NULL,
PRIMARY KEY CLUSTERED
(
[sno] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
Set nocount on
insert into Table5 values (‘a’,’b’,’c’)
go 10002

-> Checking the row count for object Table5,

Blog26_3

-> The PRIMARY DATA CENTRE goes down. 2 votes are lost as Database Server JBSERVER1 and file share witness is down. Now that 2 votes out of 3 votes are lost, the cluster goes down.

-> Checking the SQL Server instance and Eventlogs on JBSERVER2 when the Primary Data Centre is down.

Blog26_4

-> Implementing Force Quorum on JBSERVER2.

Blog26_5

-> Checking the SQL Server Instance after Force Quorum,

Blog26_6

-> I will suspend the data movement now,

Blog26_7

Blog26_8

Blog26_9

-> Right-click the availability group to be failed over, and select Failover.

Blog26_10

Blog26_11

Blog26_12

Blog26_13

Blog26_14

-> Checking the SQL Server Instance after the failover with data loss.

Blog26_15

-> The application can now connect to SQL Server Instance JBSERVER2\IN2014 using the Listener and use it. Let us insert a single row to the table for testing and make sure if it can be seen later after the failback.

insert into Table5 values (‘a’,’b’,’c’)
go

Blog26_16

-> The PRIMARY DATA CENTRE comes online. Database Server JBSERVER1 and File witness are online now.

-> Connecting to JBSERVER1\IN2014 and Suspending the data movement,

Blog26_17

Blog26_18

Blog26_19

-> We will failback the Alwayson Availability group to JBSERVER1\IN2014,

Blog26_20

Blog26_21

Blog26_22

Blog26_23

Blog26_24

Blog26_26

Blog26_27

-> On SQL Server Instance JBSERVER1\IN2014, we will resume the data movement.

Blog26_28

Blog26_29

-> On SQL Server Instance JBSERVER2\IN2014, we will resume the data movement.

Blog26_30

Blog26_31

-> Checking the SQL Server Instance now,

Blog26_32

-> Checking the row count for object Table5 on JBSERVER1\IN2014 after failback,

Blog26_33

Thank You,
Vivek Janakiraman

Disclaimer:
The views expressed on this blog are mine alone and do not reflect the views of my company or anyone else. All postings on this blog are provided “AS IS” with no warranties, and confers no rights.

Advertisements

Disaster Recovery Using AlwaysON Availability Group – Scenario 1

Environment

Blog25_1

-> Disaster Recovery scenario is as below,

  • PRIMARY DATA CENTRE goes down. 
  • The databases on Server JBSERVER2 should be made online and have the application connect to Database Server JBSERVER2. 
  • Failback Availability group back to JBSERVER1 when PRIMARY DATA CENTRE comes online. 
  • The changes made by the Application on JBSERVER2\IN2014 should be relayed to JBSERVER1\IN2014

-> Checking the current AlwaysON setup in SQL Server Management Studio,

Blog25_2

-> The Database JB_DB contains a table named Table5, which we will use for testing.

USE [JB_DB]
GO
CREATE TABLE [dbo].[Table5](
[sno] [int] IDENTITY(1,1) NOT NULL,
       [sname] [char](2000) NULL,
       [sname1] [char](2000) NULL,
[sname2] [char](2000) NULL,
PRIMARY KEY CLUSTERED
(
       [sno] ASC
)WITH (PAD_INDEX = OFF, STATISTICS_NORECOMPUTE = OFF, IGNORE_DUP_KEY = OFF, ALLOW_ROW_LOCKS = ON, ALLOW_PAGE_LOCKS = ON) ON [PRIMARY]
) ON [PRIMARY]
Set nocount on
insert into Table5 values (‘a’,’b’,’c’)
go 10002

-> Checking the row count for object Table5,

Blog25_3

-> The PRIMARY DATA CENTRE goes down. 2 votes are lost as Database Server JBSERVER1 and file share witness is down. Now that 2 votes out of 3 votes are lost, the cluster goes down.

-> Checking the SQL Server instance and Eventlogs on JBSERVER2 when the Primary Data Centre is down.

Blog25_4

-> Implementing Force Quorum on JBSERVER2.

Blog25_5

-> Checking the SQL Server Instance after Force Quorum,

Blog25_6

-> I will suspend the data movement now,

Blog25_7

Blog25_8

Blog25_9

-> Right-click the availability group to be failed over, and select Failover.

Blog25_10

Blog25_11

Blog25_12

Blog25_13

Blog25_14

-> Checking the SQL Server Instance after the failover with data loss.

Blog25_15

-> The application can now connect to SQL Server Instance JBSERVER2\IN2014 using the Listener and use it. Let us insert a single row to the table for testing and make sure if it can be seen later after the failback.

insert into Table5 values (‘a’,’b’,’c’)
go

Blog25_16

-> The PRIMARY DATA CENTRE comes online. Database Server JBSERVER1 and File witness are online now.

-> Connecting to JBSERVER1\IN2014 and Suspending the data movement,

Blog25_17Blog25_18

Blog25_19

-> On SQL Server Instance JBSERVER2\IN2014, we will resume the data movement.

Blog25_20

Blog25_21

-> On SQL Server Instance JBSERVER1\IN2014, we will resume the data movement.

Blog25_22

Blog25_23

-> Checking the SQL Server Instance now,

Blog25_24

-> We will failback the Alwayson Availability group to JBSERVER1\IN2014,

Blog25_25

Blog25_26

Blog25_27

Blog25_28

Blog25_29

Blog25_30

Blog25_31

-> Checking the row count for object Table5 on JBSERVER1\IN2014 after failback,

Blog25_32

Thank You,
Vivek Janakiraman

Disclaimer:
The views expressed on this blog are mine alone and do not reflect the views of my company or anyone else. All postings on this blog are provided “AS IS” with no warranties, and confers no rights.

Stretch database – Modifying the filter function

-> Please refer “https://jbswiki.com/2017/06/15/stretch-database-in-sql-server-2016/” if you want to setup Stretch database from scratch. If you refer the article I would have named the function “StretchByYear” in the wizard page “Select rowst  stretch”.

-> I will open the function StretchByYear to check what it contains,

Blog6_1.PNG

-> The modify script for the function is as below,

USE [JB_StretchDB]
GO
/****** Object: UserDefinedFunction [dbo].[StretchByYear] Script Date: 17/06/2017 7:59:56 PM ******/
SET ANSI_NULLS ON
GO
SET QUOTED_IDENTIFIER ON
GO
ALTER FUNCTION [dbo].[StretchByYear] (@Year Int)
RETURNS TABLE
WITH SCHEMABINDING
AS RETURN SELECT 1 AS is_eligible
WHERE @Year <= CONVERT(Int, N’1982′)

-> The modify function updates us that all rows less than or equal to 1982 will be moved to the cloud.

-> Checking the stretch monitor, We see 20000 rows on On-Premise and 30000 rows on cloud.

Blog6_2.PNG

-> The current filter function moves all data less than equal to 1982 to the cloud. Now lets consider that the  requirement changes to move all data less than equal to 1983 should be moved to cloud. In order to achieve this, I will create a new function as below,

USE [JB_StretchDB]
GO
CREATE FUNCTION [dbo].[StretchByYear_1983] (@Year Int)
RETURNS TABLE
WITH SCHEMABINDING
AS RETURN SELECT 1 AS is_eligible
WHERE @Year <= CONVERT(Int, N’1983′)
GO

-> One thing to remember is, the new filter function has to be less restrictive than the previous function.

-> Enabling the filter function for table Table1,

ALTER TABLE Table1 SET ( REMOTE_DATA_ARCHIVE = ON (
FILTER_PREDICATE = dbo.StretchByYear_1983(Year),
MIGRATION_STATE = OUTBOUND
) )

-> Executed below coommand to insert an row,

insert into Table1 values(replicate(‘A’,25),1980)

-> Now checking the Stretch monitor,

Blog6_3.PNG

-> It is clear from the screenshot above that the new filter function has taken effect.

Thank You,
Vivek Janakiraman

Disclaimer:
The views expressed on this blog are mine alone and do not reflect the views of my company or anyone else. All postings on this blog are provided “AS IS” with no warranties, and confers no rights.

Disabling Stretch Database

-> Please refer “https://jbswiki.com/2017/06/15/stretch-database-in-sql-server-2016/” if you want to setup Stretch database from scratch. In this article, I will be disabling stretch database on the SQL server instance.

-> Executing the below query to see what all tables are part of stretch database,

select object_name (object_id),* from sys.remote_data_archive_tables

Blog5_1

-> We must first disable the stretch for each individual tables before disabling it for the database.

-> Disabling it for Table1 by migrating the data back from Azure database to On-Premise database. Please note that migrating the data from azure will involve extra cost.

Blog5_2.PNG

-> Make sure we have sufficient space on the data drive to bring back the data and then click on “Yes”.

Blog5_3.PNG

Blog5_4.PNG

-> Thats quick. Usually it takes time for migrating, if the data involved is too huge.

-> Executing the below query to see what all tables are part of stretch database. We dont see Table1 anymore,

select object_name (object_id),* from sys.remote_data_archive_tables

Blog5_5.PNG

-> Checking the execution plan after executing the below query. The “Remote Query” is no longer present and the “actual number of rows” now is 50000.

select sname, year, count(*)
from Table1
group by sname,year

Blog5_6.PNG

-> Disabling stretch feature for Table2 by selecting option “Leave Data in Azure”.

Blog5_7.PNG

Blog5_8

Blog5_9

Blog5_10

-> Executing the below query to see what all tables are part of stretch database. We dont see any tables now,

select object_name (object_id),* from sys.remote_data_archive_tables

Blog5_11

-> Checking the execution plan after executing the below query. The “Remote Query” is no longer present and the “actual number of rows” now is 10000. It is clear that all the rows in azure is not migrated back to On-Premise database.

select sname, year, count(*)
from Table2
group by sname,year

Blog5_13

Blog5_12

-> Now that the tables are done, I will disable the stretch feature for the database,

Blog5_14.PNG

Blog5_15

Blog5_16

Thank You,
Vivek Janakiraman

Disclaimer:
The views expressed on this blog are mine alone and do not reflect the views of my company or anyone else. All postings on this blog are provided “AS IS” with no warranties, and confers no rights.

Adding a table to the stretch database

-> Please refer “https://jbswiki.com/2017/06/15/stretch-database-in-sql-server-2016/” if you want to setup Stretch database from scratch. In this article, I will be adding table Table3 to the existing stretch database.

-> Let’s create the required objects for this demo on the already configured Stretch database JB_StretchDB,

use JB_StretchDB
go
create table Table3(
sno int primary key identity (1,1),
sname varchar(255),
Year int)

-> Populating tables Table3 with some data,

set nocount on
insert into Table3 values(replicate(‘A’,25),1980)
go 10000
insert into Table3 values(replicate(‘B’,25),1981)
go 10000
insert into Table3 values(replicate(‘C’,25),1982)
go 10000
insert into Table3 values(replicate(‘D’,25),1983)
go 10000
insert into Table3 values(replicate(‘E’,25),1984)
go 10000

-> Looking at the data,

select sname, year, count(*)
from Table3
group by sname,year

Blog4_1

-> Select the table that will be added to stretch database and perform as shown in the screenshot,

Blog4_2

Blog4_3

-> Click on “Entire Table” under “Migrate”.

Blog4_4

Blog4_5.PNG

Blog4_6.PNG

Blog4_7

Blog4_8.PNG

-> Monitoring the status for table3,

Blog4_9.PNG

Blog4_10.PNG

-> Executing the below query and looking at the execution plan. The execution plan shows us that we are querying 10000 rows from the On-Premise database and 40000 rows from the Azure database.

select sname, year, count(*)
from Table3
group by sname,year

Blog4_11.PNG

Thank You,
Vivek Janakiraman

Disclaimer:
The views expressed on this blog are mine alone and do not reflect the views of my company or anyone else. All postings on this blog are provided “AS IS” with no warranties, and confers no rights.

Stretch Database in SQL Server 2016

We can use the stretch database to place our less-frequently accessed data securely in Microsoft Azure.

Benefits

-> Cost effective – The less-frequently accessed data can be stored on cost efficient and secure Microsoft Azure than storing them on costly On-premise storage.

-> No changes in queries – The queries that access a stretch database can be same and no additional logic is required to incorporate the data moved to Microsoft Azure.

-> Database Maintenance – Database maintenance will be comparably faster as we will touch only the frequently accessed data.

-> Faster queries – Queries touching frequently accessed database will be comparably faster with fewer IO and increased performance.

Blog1_Azure_visio

-> Let’s create the required database and objects for this demo,

create database JB_StretchDB
go
use JB_StretchDB
go
create table Table1(
sno int primary key identity (1,1),
sname varchar(255),
Year int)

-> Populating table Table1 with some data,

set nocount on
insert into Table1 values(replicate(‘A’,25),1980)
go 10000
insert into Table1 values(replicate(‘B’,25),1981)
go 10000
insert into Table1 values(replicate(‘C’,25),1982)
go 10000
insert into Table1 values(replicate(‘D’,25),1983)
go 10000
insert into Table1 values(replicate(‘E’,25),1984)
go 10000

-> Looking at the data,

select sname, year, count(*)
from Table1
group by sname,year

Blog3_1

-> The query completes in 60 MS.

Blog3_2

-> Select the database that will be part of stretch database,

Blog3_3.png

Blog3_4.png

-> Select the table and click on “Entire Table” under “Migrate”.

Blog3_5.png

-> You can move all the data to cloud or a certain number of rows. I will select “Choose Rows” in the below screen as I want the latest data in On-Premise database and just the old data’s be moved to cloud.

Blog3_6.png

Blog3_7.png

-> I already have a Microsoft azure instance created. Hence I will select “Existing server” and point the instance from the drop down box. You can create one yourself by using the article https://jbswiki.com/2017/05/31/creating-a-sql-database-in-microsoft-azure-portal/ or you can select “Create new server” and proceed.

Blog3_8.png

-> Provide the password for the database master key.

Blog3_9

Blog3_10

Blog3_11

Blog3_12

-> This is what I see in the SSMS after setting up the stretch database.

Blog3_13.png

-> Executing the below query and checking the execution plan. The query actually took 19 seconds.

Blog3_14.png

-> It is clear from the screenshot that we are spending most of our time on the remote query as we are querying close to 40000 rows from Azure database.

Blog3_15.png

-> The performance is not that great, but we create stretch database just to move data to cloud that are not frequently accessed.

Thank You,
Vivek Janakiraman

Disclaimer:
The views expressed on this blog are mine alone and do not reflect the views of my company or anyone else. All postings on this blog are provided “AS IS” with no warranties, and confers no rights.

Restore on-Premise SQL server database to Azure SQL Database

-> We need to restore the database from on-Premise to Azure SQL database.

-> On-Premise database JB_test has two tables and let’s check the row count,

Blog2_1

1) Moving only the schema from on-Premise SQL database to Azure SQL database,

-> Right click on-Premise database -> Tasks -> “Extract Data-tier Application…” as shown in the screenshot below,

Blog2_2

-> Click on next,

Blog2_3

-> Provide the location where the file should be placed,

Blog2_4

Blog2_5

Blog2_6

-> Once the dacpac file is created. Get onto the SQL azure database, right click “Databases” and select “Deploy Data-tier Application”.

Blog2_7

Blog2_8

-> Specify the dacpac file,

Blog2_9

Blog2_10

Blog2_11

Blog2_12

-> It is complete and we see the database in Azure,

Blog2_13

2) Moving schema and data from on-Premise SQL database to Azure SQL database,

-> Right click on-Premise database -> Tasks -> “Export Data-tier Application…” as shown in the screenshot below,

Blog2_14

-> Click on next,

Blog2_15

-> Provide the location where the file should be placed,

Blog2_16

Blog2_17

Blog2_18

Blog2_19

-> Once the bcpac file is created. Get onto the SQL azure database, right click “Databases” and select “Import Data-tier Application”.

Blog2_20

Blog2_21

-> Specify the bacpac file,

Blog2_22

Blog2_23

-> When I clicked “Next” I got the below message,

Blog2_24

TITLE: Microsoft SQL Server Management Studio
——————————
An exception occurred while executing a Transact-SQL statement or batch. (Microsoft.SqlServer.ConnectionInfo)
—————————-
ADDITIONAL INFORMATION:
The connection is broken and recovery is not possible. The client driver attempted to recover the connection one or more times and all attempts failed. Increase the value of ConnectRetryCount to increase the number of recovery attempts. (Microsoft SQL Server, Error: 0)
——————————
Cannot open database “JB_test” requested by the login. The login failed.
Login failed for user ‘JBAdmin’. (Microsoft SQL Server, Error: 4060)

-> I don’t have the database “JB_test” on the instance, so I was not sure why I was getting this error. Later I understood the isssue, It seems like I have created a database JB_Test before 1 hour with the same name JB_Test and dropped it and that is causing the isssue. I spoke to one of the Azure expert and he pointed out that even though we delete the database, the database will be there hidden for atleast 1 day. Instead of waiting for 1 day, I used a different name and started the import.

Blog2_25

Blog2_26

Blog2_27

Blog2_28

Blog2_29

-> It is complete and we see the database JB_TestWithData as an Azure SQL Database,

Blog2_30

Thank You,
Vivek Janakiraman

Disclaimer:
The views expressed on this blog are mine alone and do not reflect the views of my company or anyone else. All postings on this blog are provided “AS IS” with no warranties, and confers no rights.