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Thursday, 7 February 2013

Database Migration in SQL Server



SQL Server Database Migration Checklist
 Many times we get requests to migrate a single user database or multiple user databases to different server. At the time of migrating databases, there are chances that we can miss some important steps, for example trustworthy property, dependent jobs, linked server, logins etc. There are also chances we are missing important DBA items which can hurt SQL Server performance.  In this tip, I cover tasks that should be followed when moving databases from one server to another server.

Solution
As a solution to decrease making mistakes during the migration process I have developed the below database migration checklist. In addition, there are steps which should be taken which can enhance the database performance after the migration.


Pre-Migration Checklist
  1. Analyze the disk space of the target server for the new database, if the disk space is not enough add more space on the target server
  2. Confirm the data and log file location for the target server
  3. Collect the information about the Database properties (Auto Stats, DB Owner, Recovery Model, Compatibility level, Trustworthy option etc)
  4. Collect the information of dependent applications, make sure application services will be stopped during the database migration
  5. Collect the information of database logins, users and their permissions. (Optional)
  6. Check the database for the Orphan users if any
  7. Check the SQL Server for any dependent objects (SQL Agent Jobs and Linked Servers)
  8. Check, if the database is part of any maintenance plan


Below are various scripts you can run to collect data.
Script to Check the Disk and Database Size
-- Procedure to check disc space
exec master..xp_fixeddrives
-- To Check database size
exec sp_helpdb [dbName]
or
use [dbName]
select str(sum(convert(dec(17,2),size)) / 128,10,2)  + 'MB'
from dbo.sysfiles
GO
Script to Check Database Properties
select
 sysDB.database_id,
 sysDB.Name as 'Database Name',
 syslogin.Name as 'DB Owner',
 sysDB.state_desc,
 sysDB.recovery_model_desc,
 sysDB.collation_name,
 sysDB.user_access_desc,
 sysDB.compatibility_level,
 sysDB.is_read_only,
 sysDB.is_auto_close_on,
 sysDB.is_auto_shrink_on,
 sysDB.is_auto_create_stats_on,
 sysDB.is_auto_update_stats_on,
 sysDB.is_fulltext_enabled,
 sysDB.is_trustworthy_on
from sys.databases sysDB
INNER JOIN sys.syslogins syslogin ON sysDB.owner_sid = syslogin.sid
Another Script to Check Database Properties
declare @dbdesc varchar(max)
declare @name varchar(10)
set @name='Master'
SELECT @dbdesc = 'Status=' + convert(sysname,DatabasePropertyEx(@name,'Status')) 
SELECT @dbdesc = @dbdesc + ', Updateability=' + convert(sysname,DatabasePropertyEx(@name,'Updateability')) 
SELECT @dbdesc = @dbdesc + ', UserAccess=' + convert(sysname,DatabasePropertyEx(@name,'UserAccess')) 
SELECT @dbdesc = @dbdesc + ', Recovery=' + convert(sysname,DatabasePropertyEx(@name,'Recovery')) 
SELECT @dbdesc = @dbdesc + ', Version=' + convert(sysname,DatabasePropertyEx(@name,'Version')) 
 
 -- These props only available if db not shutdown 
 IF DatabaseProperty(@name, 'IsShutdown') = 0 
 BEGIN 
  SELECT @dbdesc = @dbdesc + ', Collation=' + convert(sysname,DatabasePropertyEx(@name,'Collation')) 
  SELECT @dbdesc = @dbdesc + ', SQLSortOrder=' + convert(sysname,DatabasePropertyEx(@name,'SQLSortOrder')) 
 END 
 
 -- These are the boolean properties 
 IF DatabasePropertyEx(@name,'IsAutoClose') = 1 
  SELECT @dbdesc = @dbdesc + ', ' + 'IsAutoClose' 
 IF DatabasePropertyEx(@name,'IsAutoShrink') = 1 
  SELECT @dbdesc = @dbdesc + ', ' + 'IsAutoShrink' 
 IF DatabasePropertyEx(@name,'IsInStandby') = 1 
  SELECT @dbdesc = @dbdesc + ', ' + 'IsInStandby' 
 IF DatabasePropertyEx(@name,'IsTornPageDetectionEnabled') = 1 
  SELECT @dbdesc = @dbdesc + ', ' + 'IsTornPageDetectionEnabled' 
 IF DatabasePropertyEx(@name,'IsAnsiNullDefault') = 1 
  SELECT @dbdesc = @dbdesc + ', ' + 'IsAnsiNullDefault' 
 IF DatabasePropertyEx(@name,'IsAnsiNullsEnabled') = 1 
  SELECT @dbdesc = @dbdesc + ', ' + 'IsAnsiNullsEnabled' 
 IF DatabasePropertyEx(@name,'IsAnsiPaddingEnabled') = 1 
  SELECT @dbdesc = @dbdesc + ', ' + 'IsAnsiPaddingEnabled' 
 IF DatabasePropertyEx(@name,'IsAnsiWarningsEnabled') = 1 
  SELECT @dbdesc = @dbdesc + ', ' + 'IsAnsiWarningsEnabled' 
 IF DatabasePropertyEx(@name,'IsArithmeticAbortEnabled') = 1 
  SELECT @dbdesc = @dbdesc + ', ' + 'IsArithmeticAbortEnabled' 
 IF DatabasePropertyEx(@name,'IsAutoCreateStatistics') = 1 
  SELECT @dbdesc = @dbdesc + ', ' + 'IsAutoCreateStatistics' 
 IF DatabasePropertyEx(@name,'IsAutoUpdateStatistics') = 1 
  SELECT @dbdesc = @dbdesc + ', ' + 'IsAutoUpdateStatistics' 
 IF DatabasePropertyEx(@name,'IsCloseCursorsOnCommitEnabled') = 1 
  SELECT @dbdesc = @dbdesc + ', ' + 'IsCloseCursorsOnCommitEnabled' 
 IF DatabasePropertyEx(@name,'IsFullTextEnabled') = 1 
  SELECT @dbdesc = @dbdesc + ', ' + 'IsFullTextEnabled' 
 IF DatabasePropertyEx(@name,'IsLocalCursorsDefault') = 1 
  SELECT @dbdesc = @dbdesc + ', ' + 'IsLocalCursorsDefault' 
 IF DatabasePropertyEx(@name,'IsNullConcat') = 1 
  SELECT @dbdesc = @dbdesc + ', ' + 'IsNullConcat' 
 IF DatabasePropertyEx(@name,'IsNumericRoundAbortEnabled') = 1 
  SELECT @dbdesc = @dbdesc + ', ' + 'IsNumericRoundAbortEnabled' 
 IF DatabasePropertyEx(@name,'IsQuotedIdentifiersEnabled') = 1 
  SELECT @dbdesc = @dbdesc + ', ' + 'IsQuotedIdentifiersEnabled' 
 IF DatabasePropertyEx(@name,'IsRecursiveTriggersEnabled') = 1 
  SELECT @dbdesc = @dbdesc + ', ' + 'IsRecursiveTriggersEnabled' 
 IF DatabasePropertyEx(@name,'IsMergePublished') = 1 
  SELECT @dbdesc = @dbdesc + ', ' + 'IsMergePublished' 
 IF DatabasePropertyEx(@name,'IsPublished') = 1 
  SELECT @dbdesc = @dbdesc + ', ' + 'IsPublished' 
 IF DatabasePropertyEx(@name,'IsSubscribed') = 1 
  SELECT @dbdesc = @dbdesc + ', ' + 'IsSubscribed' 
 IF DatabasePropertyEx(@name,'IsSyncWithBackup') = 1 
  SELECT @dbdesc = @dbdesc + ', ' + 'IsSyncWithBackup' 
SELECT @dbdesc
Script to List Orphan Users
sp_change_users_login 'report'
GO
Script to List Linked Servers
select  *
from sys.sysservers
Script to List Database Dependent Jobs
select
 distinct
 name,
 database_name
from sysjobs sj
INNER JOIN sysjobsteps sjt on sj.job_id = sjt.job_id


Database Migration Checklist
These are the steps you would go through to make the change.
1. Stop the application services
2. Change the database to read-only mode (Optional)
-- Script to make the database readonly
USE [master]
GO
ALTER DATABASE [DBName] SET  READ_ONLY WITH NO_WAIT
GO
ALTER DATABASE [DBName] SET  READ_ONLY
GO
3. Take the latest backup of all the databases involved in migration
4. Restore the databases on the target server on the appropriate drives
5. Cross check the database properties as per the database property script output, change the database properties as per the pre migration- checklist
Script to Change DB Owner
This will change the database owner to "sa".  This can be used to change to any owner you would like.
 USE databaseName
EXEC sp_changedbowner 'sa'
Script to Turn on Trustworthy Option
If trustworthy option was set, this will turn it on for the database.
 ALTER DATABASE database_name SET TRUSTWORTHY ON
Script to Change the Database Compatibility Level
When you upgrade to a new version, the old compatibility level will remain.  This script shows how to change the compatibility level to SQL Server 2005 compatibility .
ALTER DATABASE DatabaseName
SET SINGLE_USER
GO
EXEC sp_dbcmptlevel DatabaseName, 90;
GO
ALTER DATABASE DatabaseName
SET MULTI_USER
GO
6. Execute the output of Login transfer script on the target server, to create logins on the target server you can get the code from this technet article: http://support.microsoft.com/kb/246133.

7. Check for Orphan Users and Fix Orphan Users
Script to Check and Fix Orphan Users
-- Script to check the orphan user
EXEC sp_change_users_login 'Report'
--Use below code to fix the Orphan User issue
DECLARE @username varchar(25)
DECLARE fixusers CURSOR
FOR
SELECT UserName = name FROM sysusers
WHERE issqluser = 1 and (sid is not null and sid <> 0x0)
and suser_sname(sid) is null
ORDER BY name
OPEN fixusers
FETCH NEXT FROM fixusers
INTO @username
WHILE @@FETCH_STATUS = 0
BEGIN
EXEC sp_change_users_login 'update_one', @username, @username
FETCH NEXT FROM fixusers
INTO @username
END
CLOSE fixusers
DEALLOCATE fixusers
8. Execute DBCC UPDATEUSAGE on the restored database.

Run the DBCC UPDATEUSAGE command against the migrated database when upgrading to a newer version of SQL Server.
DBCC UPDATEUSAGE('database_name') WITH COUNT_ROWS
DBCC CHECKDB
OR
DBCC CHECKDB('database_name') WITH ALL_ERRORMSGS
9. Rebuild Indexes (Optional) As per the requirement and time window you can execute this option.
Take a look at this tip to rebuild all indexes.
This will rebuild or reorganize all indexes for a particular table.

Index Rebuild :- This process drops the existing Index and Recreates the index.
Index Reorganize :- This process physically reorganizes the leaf nodes of the index.
-- Script for Index Rebuild
USE [DBName];
GO
ALTER INDEX ALL ON [ObjectName] REBUILD
GO
-- Script for Index Reorganize
USE AdventureWorks;
GO
ALTER INDEX ALL ON [ObjectName] REORGANIZE
GO
sp_updatestats
11. Recompile procedures
Take a look at this tip to recompile all objects.
This will recompile a particular stored procedure.
sp_recompile 'procedureName'
12. Start the application services, check the application functionality and check the Windows event logs.

13. Check the SQL Server Error Log for login failures and other errors
Take a look at this tip on how to read SQL Server error logs.
EXEC xp_readerrorlog 0,1,"Error",Null
14. Once the application team confirms that application is running fine take the databases offline on the source server or make them read only
-- Script to make the database readonly
USE [master]
GO
ALTER DATABASE [DBName] SET  READ_ONLY WITH NO_WAIT
GO
ALTER DATABASE [DBName] SET  READ_ONLY
GO
-- Script to take the database offline
EXEC sp_dboption N'DBName', N'offline', N'true'
OR
ALTER DATABASE [DBName] SET OFFLINE WITH
ROLLBACK IMMEDIATE
Next Steps
  • Test the process to determine how much time and disk space would be needed by using the backup and recovery process.
  • Meet with your technical and business teams to find out how much time is available for the migration and plan the activity
  • Design the rollback plan, if the application is not working fine
  • Add more migration cases in your checklist, for example check if the database requires any server level change (For example CLR, XP_Cmdshell etc)
  • Some of these scripts give you the base command to update a portion of the data, enhance the process to hit each object in your database.