In this post, I am sharing different types of options to copy your MySQL Database from one server to another server.

The migration of data, objects or database is a ubiquitous task for any DBA so as a blogger I can’t skip this kind of topics.

Common and General option:

Server 1: Take the backup in .sql file
– -databases option adds the CREATE DATABASE in dump file, so that you can restore same backup in any other server without creating a blank database.

my-shell> mysqldump --databases db_name > mydump.sql

Next, copy mydump.sql file from Server 1 to Server 2.

Server 2: Restore the backup

my-shell> mysql < mydump.sql

My favourite option:

Use pipe and copy the database from one server to another, without taking or moving the physical file.

mysqldump -uuser -ppassword db_name | mysql -hremoteserver -uremoteuser -premoteserverpassword

For all database:

mysqldump --all-databases -uuser -ppassword | mysql -hremoteserver -uremoteuser -premoteserverpassword

In this post, I am sharing a solution to take an only table or few tables backup in MySQL and also sharing solution like, How you can ignore few tables while taking a backup of MySQL Database.

In last year, I shared a basic article on how to take a backup of the database in MySQL, which also you can access here.

MySQL: Backup and Restore Database using mysqldump

The copying data from one server to another, data migration, the backup requirement for specific data or object or stored procedure, data versioning – These all are part of DBA’s day to day activity, and N number combinations are there.

There are many options available for mysqldump utility, so I am using few options to play for table backup only. Let me explore few options related to table backup in MySQL.

Take a backup of a single table:

mysqldump -u  -p db_name table_name > table_name_backup.sql

Take a backup of multiple tables:

mysqldump -u <db_username> -p db_name table_name_1 table_name_2 table_name_3 > tables_backup.sql

Ignore a table from full database backup:

mysqldump -u <db_username> -p db_name --ignore-table=db_name.table_name_1 > db_backup.sql

I have published my first guest post on www.sqlmvp.org.
I have written about SQL Server Strip Database Backup and Restore for the large size of the Database.

Here, You can visit this article.

SQL Server: Have a large Database, use Striped Database Backup & Restore

In our organization, junior database developers are learning PostgreSQL, and they require a sample database from our Validation Database Server.

In this scenario, Database Administrator takes PostgreSQL backup using pg_dump utility and restore that dump into the development environment.

A pg_dump is a PostgreSQL utility which is used for PostgreSQL database backup and restore.

Another option is, directly copy the database from one server to another server using pg_dump + psql. In this scenario, Database Administrator does not require any intermediate database backup file.

Open your windows command prompt and go to \PostgreSQL\bin directory where you can execute and test below two different commands.

Copy database from one server to another server (using, pg_dump | psql):

pg_dump -h host1 dbname | psql -h host2 dbname

Copy database, Using pg_dump utility for backup and restore:

Take full database backup:

pg_dump -U username database_name > filepath\backup.sql

Restore database backup:

pg_dump -U username database_name < filepath\backup.sql

PostgreSQL: File System Level Backup to just Copy DATA Directory

Suppose I have a Database maintenance plan which runs every 15 minutes to take the Transaction Logs backup of all user defined databases. One of the members of DBA team created a new database in the morning at 09:10 AM and the DB maintenance job started failing. What could be the reason?

This job is failing because the we did not take a full database backup of the newly created database. We need to a full backup of a database to initiate the log chain.

Is it possible to restore a Database backup of SQL Server 2012 to SQL Server 2008 /2008 R2?

No it’s not possible to restore the upper version database backup to lower version.

What is RESTORE LABELONLY option?

It returns a result set containing information about the backup media identified by the given backup device.

T-SQL script for RESTORE LABELONLY.

RESTORE LABELONLY FROM DISK='D:\MyDrive\Adv_Full.bak'

What is a RESTORE HEADERONLY OPTION?

It is used to check the content of a backup file.

T-SQL Script for RESTORE HEADERONLY.

RESTORE HEADERONLY 
FROM DISK = N'C:\AdventureWorks2012.bak'

How to remove all backup history from the related system tables?

Using this system stored procedure – sp_delete_backuphistory.

What are the permissions required to perform backup and Restore?

Backup:

sysadmin – fixed server role

db_owner –  fixed database role

db_backupoperator – fixed database role

Restore:

Sysadmin – fixed server role

Dbcreator – fixed server role

db_owner – fixed database role

You are taking full database backup, differential database backups, and transaction log backups. If your system is crashed and some of the differential database also crashed, can you recover the database to the current point in time with out differential backups.

Yes,

You can recover to the current point in time, as long as you have all the transaction log backups available and they are all valid. Differential backups do not affect the transaction log backup chain.

What is BACKUP WITH TRUNCATE_ONLY option?

TRUNCATE_ONLY doesn’t back up the transaction log; it simply forces SQL Server to take a checkpoint, which then truncates the log, getting rid of inactive entries and shrinking the size of the log file.

What is the meaning of RetainDays Property?

The RetainDays property specifies the number of days that must elapse before a backup set can be overwritten.

If your database size is 800 GB and daily 6000 transactions are running, what should be your backup plan.

• Weekly Full backup
• Daily Differential backup
• After every 30 min Transaction log backup

What kind of common issues with Log Restores?

• an incomplete series of log backup files.
• a missing full backup database file.
• minimally logged transactions in a log file, when database is operating in the BULK_LOGGED recovery model.

Can I restore a backup onto a different version of SQL Server?

You can restore to a different version of SQL Server, but you can only restore upwards. In other words, you can restore from 2000 to 2005 or from 2005 to 2008R2 or from 2008 to 2012, but you can never restore in the reverse direction.

How to make your database into single user mode?

ALTER DATABASE Database_Name SET SINGLE_USER;

How to make your database into multi user mode?

ALTER DATABASE Database_Name SET MULTI_USER;

How to make your database into emergency mode?

ALTER DATABASE Database_Name SET EMERGENCY;

How you estimate the size of full database backup?

You can estimate the size of a full database backup by using the sp_spaceused system stored procedure.

What is the BACKUP WITH EXPIREDATE option?

The EXPIREDATE option to determine when the SQL Server Database Engine can overwrite the backup.

T-SQL script to take database backup WITH EXPIREDATE.

BACKUP DATABASE AdventureWorks2012
TO DISK = 'D:\AdventureWorks2012.Bak'
WITH EXPIREDATE = '08/08/2016' ;

We have a production server containing three actively-used databases. The application owner informs us that no more than two hours of data loss

can be tolerated, in the event of corruption or any other disaster. None of the databases are complex structurally, each containing just one data file and one log file and each database operating in the FULL recovery model.

What should be your database backup plan in the above scenario?

• Perform full nightly database backups for every database (plus the system databases).
• Perform log backups on the user databases every 2 hours, on a schedule starting after the full backups are complete and ending before the full backup jobs starts.

We have a production database system that contains three databases with complex data structures. Each database comprises multiple data files split into two filegroups, one read-only and one writable. The read-only file group is updated once per week with newly archived records. The writable file groups have an acceptable data loss of 1 hour. Most database activity on this server will take place during the day and each database operating in the FULL recovery model.

What should be your database backup plan in the above scenario?

• Perform nightly full database backups for all system databases.
• Perform a weekly full file backup of the read-only filegroups on each user database, after the archived data has been loaded.
• Perform nightly full file backups of the writable file groups on each user database.
• Perform hourly log backups for each user database; the log backup schedule should start after the nightly full file backups are complete, and finish one hour before the full file backup processes start again.

If I leave a backup on a network share, surely nobody can read it?

Unless you encrypt the backup file directly, then yes, that is a readable file. If someone got access to the network share, he or she could read the backup file directly using a text editor, or simply copy the file and run a restore on another instance of SQL Server.

Does a backup contain more than the data?

A backup does contain more than just the data. It contains the entire structure of the database. This includes all the data structures and data, of course, but it also includes all the procedures, views, functions and any other code. It also contains the settings and definitions of the database.

When is a Page Restore Userful?

A page restore is intended for repairing isolated damaged pages. Restoring and recovering a few individual pages might be faster than a file restore, reducing the amount of data that is offline during a restore operation.

T-SQL syntax to restore corrupted pages.

RESTORE DATABASE database_name PAGE='1:57, 1:202, 1:916, 1:1016' 
FROM 'file_path'
WITH NORECOVERY;

How to find corrupted data pages?

Use suspect_pages table of MSDB database to find information of corrupted data pages.

Pages are listed in this table because they are suspected of being bad, but they might actually be fine. When a suspect page is repaired, its status is updated in the event_type column.

Can I perform Online page restore on all the edition of SQL Server?

SQL Server Enterprise edition supports online page restores, though they use offline restore if the database is currently offline. In most cases, a damaged page can be restored while the database remains online.

Meaning of different event type of suspect_pages table.

• 1 = An 823 error that causes a suspect page (such as a disk error) or an 824 error other than a bad checksum or a torn page (such as a bad page ID).
• 2 = Bad checksum.
• 3 = Torn page.
• 4 = Restored (page was restored after it was marked bad).
• 5 = Repaired (DBCC repaired the page).
• 7 = Deallocated by DBCC.

Why ApexSQL Recovery tool is better point-in-time recovery?

The advantages of ApexSQL tools over recovery to a point in time are that ApexSQL will recover just the tables you specify, while a point-in-time recovery will roll back all the transactions that happened in the meantime.

What is a Snapshot Backups?

A snapshot backup is a specialized backup that is created almost instantaneously by using a split-mirror solution obtained from an independent hardware and software vendor. Snapshot backups minimize or eliminate the use of SQL Server resources to accomplish the backup.

This is especially useful for moderate to very large databases in which availability is very important.

What are the benefits of Snapshot Backups?

• A backup can be created quickly, typically measured in seconds, with little or no effect on the server.
• A restore operation can be accomplished from a disk backup just as quickly.
• Backup to tape can be accomplished by another host without an effect on the production system.
• A copy of a production database can be created instantly for reporting or testing.

How to reduce the size of Log files?

• Perform a full backup of your database.
• Change the backup method of your database to “Simple”.
• Open a query window and enter “checkpoint” and execute.
• Perform another backup of the database.
• Change the backup method of your database back to “Full”.
• Perform a final full backup of the database.

Will differential backups always be smaller than full backups?

For the most part, if you refresh your base backup on a regular schedule, you will find that a differential backup should be smaller in size than a full database backup. However, there are situations where a differential backup could become even larger than its corresponding base backup, for example if the base backup is not refreshed for a long period and during that time a large amount of data has been changed or added.

Have you ever failed to get exclusive access for MSDB?

Yes, If SQL Server Agent service is running, exclusive access cannot be achieved. To get an exclusive access, you should stop the SQL Agent service.

Which are the popular SQL Server Backup Encryption tools?

• SQL Safe Backup (IDERA)

• SQL Backup And FTP (Pranas.NET)

• SQL Backup Pro (Red Gate Software)

• LiteSpeed for SQL Server (Quest Software)

• ApexSQL for advance backup and recovery.

Can you access the database during a restore operation?

Most SQL Server restores are offline operations; users can’t access the database while it’s being restored.

With the full recovery model, partial restores and restores of nonprimary file groups are online operations by default.

How can we rebuild the system databases?

Please visit this official Microsoft document.

Can I backup MS SQL Server ‘tempdb’ database?

No. You cannot backup your MS SQL Server ‘tempdb’ database.

In which scenarios Transaction Log is truncated?

When checkpoint runs in SIMPLE recovery model and Transaction Log Backup was generated in Full recovery model. It truncates all committed transactions from the log file.

What are the different states, in which we cannot take backup of database?

• Suspect (only tail log backup is allowed)
• Restoring
• Standby
• Offline
• Transaction Log file was full(Only Log backups are allowed)

How to turn off logging of all successful backups in your SQL Server error logs?

Using trace flag 3226.

DBCC TRACEON (3226,-1)

T-SQL script to take a database backup.

BACKUP DATABASE AdventureWorks2012 TO DISK='e:\advwork.bak'

Backup to multiple files using T-SQL.

BACKUP DATABASE AdventureWorks2012 TO 
DISK='e:\advwork.bak'
,DISK='d:\advwork.bak'
,DISK='f:\advwork.bak'

T-SQL script to restore a database.

RESTORE DATABASE AdventureWorks2012 FROM DISK='e:\advwork.bak'

T-SQL script to set RECOVERY FULL model.

ALTER DATABASE dbrnd_DB SET RECOVERY FULL;

T-SQL script to take Database Log backup.

BACKUP LOG dbrnd_DB TO DISK = 'd:\dbrnd\dbrnd_tran01.trn'  WITH retaindays = 3

T-SQL script to restore a multiple transaction log backups.

RESTORE DATABASE AdventureWorks2012
FROM AdventureWorks2012_1
WITH NORECOVERY;
GO

RESTORE LOG AdventureWorks2012
FROM AdventureWorks2012_log
WITH FILE = 1,
NORECOVERY;
GO

RESTORE LOG AdventureWorks2012
FROM AdventureWorks2012_log
WITH FILE = 2,
WITH NORECOVERY;
GO

RESTORE LOG AdventureWorks2012
FROM AdventureWorks2012_log
WITH FILE = 3,
WITH NORECOVERY;
GO

RESTORE DATABASE AdventureWorks2012
WITH RECOVERY;
GO

Consider a situation where database backup size is 80 GB and you have three different disks and each has 30 GB free space.

Now the question is, can you split your database backups?

Yes, it is possible. We can split the backup files into different places and the same can be restored.

BACKUP DATABASE AdventureWorks
TO DISK = ‘D:\AdventureWorks1.bak’,
DISK = ‘E:\AdventureWorks2.bak’,
DISK = ‘F:\AdventureWorks3.bak’

RESTORE DATABASE [AdventureWorks]
FROM DISK = ’D:\Backup\MultiFile\AdventureWorks1.bak’,
DISK = ’E:\AdventureWorks2.bak’,
DISK = ’F:\AdventureWorks3.bak’

We have configured every Sunday 11pm FULL backup. Every 11pm differential backups and every 1h.r transaction log backups.

The Database was failed at 11.30 pm on Friday. Then what are the database recovery steps?

• Take Tail log backup to get 11-11.30pm transactions on Friday.
• Restore last Sunday full backup with NO_RECOVERY.
• Restore Friday 11pm differential backup with NO_RECOVERY.
• Restore tail log backup with RECOVERY.

What is File or File Group backup?

Using the file or filegroup backup you can backup an entire filegroup or files within the filegroup. These backups are essential when the database size is so large that backups must be done in parts because it takes too long to backup the entire database.

T-SQL Script to take File Group backup.

BACKUP DATABASE AdventureWorks2012 FILEGROUP='PRIMARY', FILEGROUP ='Secondary'
TO DISK ='D:\AdventureWorks2012_FileGroup.bak'

What is Mirrored backup?

Mirrored database backups can be used to create multiple copies of the database backups on different locations.

T-SQL Script to take Mirrored backup.

BACKUP DATABASE AdventureWorks2012
TO DISK = ‘C:\AdventureWorks2012.bak’
MIRROR TO DISK = ‘D:\AdventureWorks2012_mirror.bak’

What is a log chain?

A continuous sequence of log backups is called a log chain. A log chain starts with a full backup of the database. Usually, a new log chain is only started when the database is backed up for the first time or after the recovery model is switched from simple recovery to full or bulk-logged recovery.

Is it possible in any situation when differential backup grows more than the Full backup?

Yes, it is possible in case when you do not take Full backup of the database for months and change in the databases grow more than the size of the Full backup.

Is it mandatory to take a Full backup if we switch the recovery model of a database?

Yes, It is mandatory to take a Full backup of the database after switching the recovery model of the database to initiate the log chain. Otherwise Diff. or Transaction logs will fail.

What is the below error?

Msg 3023, Level 16, State 2, Line 1

Backup and file manipulation operations (such as ALTER DATABASE ADD FILE) on a database must be serialized. Reissue the statement after the current backup or file manipulation operation is completed.

This error occurs when we try to run a backup, shrink, or alter database command in SQL Server in parallel.

Can you take differential backup of Master Database?

No, differential backup of master database is not allowed.

Can you take backup of a database which is in emergency mode?

We can’t take the database backup if the database is in emergency mode.

SQL Server has native backup. Why pay money for a tool to do it?

SQL Server backups work extremely well, but you’re going to have to do some work to get them set up and even more to get them automated.

A good third party product will make this automation process very simple.

For example, some tools more efficient at compressing backups, saving even more disk space and time during your backup processes.

What is the difference between Hot and Cold Backup?

Performing backup while the database is online is called Hot backup. Stopping SQL server service and copying MDF and LDF files is called cold backup which is not really happening in production.

Can I backup databases from multiple instances of MS SQL Server?

Yes. You can backup databases from multiple instances of MS SQL Server running on your local computer. However, you may not be able to backup the databases from multiple instances of the MS SQL Server hosted at multiple locations in your network.

Can you perform Log shipping and Mirroring using Simple Recovery Model?

No, You cannot perform Log shipping and Mirroring with Simple Recovery Model.

Can we perform a SQL Server compressed backup?

Starting SQL Server 2008, we can perform a compressed backup. All types of backups can be performed with compressed option.

When a checkpoint file is updated?

• Database file creation and zeroing is completed.
• After each backup set is processed.
• The redo part of a recovery is finished.

If your database size is bigger, why database backup performance is important?

It reduces the time that the extra I/O workload (and potentially CPU workload for compressed backups) is present on the system.

It reduces the potential for the transaction log file to have to grow to accommodate the transaction log generated while a backup operation is running, especially for long-running full database backups.

How you are improving your backup performance?

The easiest way to improve backup performance is to allow the backup operation to parallelize, which is known as backup striping.

By default, there’s a single data reader thread for each drive letter or mount point being read from and a single data writer thread for each backup device being written to.

In general, having more reader and writer threads should improve performance up to the point where the I/O subsystem becomes a bottleneck either for reads or writes.

A more advanced way to improve backup performance is to manually specify the number of backup I/O buffers to use (with the BUFFERCOUNT option) and the size of each buffer (with the MAXTRANSFERSIZE option).

What do you suggest to improve backup performance?

• Backup stripping / perform parallel with multiple backup device.
• Setting of maxtransfersize parameter.
• Setting of buffercount parameter.
• Setting of compression parameter.

What is Native Backup Compression (SQL Server 2008)?

Database backup compression helps in creating a database backup in a compressed format.

T-SQL Script to take compressed backup.

BACKUP DATABASE AdventureWorks2012
TO  DISK = D:\Backup\AW2012_compress.bak'
WITH COMPRESSION

T-SQL Script to calculate compression ratio.

SELECT backup_size/compressed_backup_size
FROM msdb..backupset

How compressed backup impact to the performance of the database?

By default, compression significantly increases CPU usage, and the additional CPU consumed by the compression process might adversely impact concurrent operations.

What are the restrictions of compressed backup?

• Compressed and uncompressed backups cannot co-exist in a media set.
• Previous versions of SQL Server cannot read compressed backups.
• NTbackups cannot share a tape with compressed SQL Server backups.

My backup was failed what may be the possible scenarios?

• Disk was Full or Server was busy.
• May be problem with the network.
• If the domain is not running and SQL Server service is running with domain account.
• Problem with MSDB and SQL Agent.
• Error while reading the transaction log file.
• CHECKSUM errors
• Database has entered into Suspect and restoring mode.
• Transaction log file is full.

What is RESTORE WITH RESTART option?

RESTORE WITH RESTART option, which lets you restart an interrupted restore operation. Periodically, a restore operation writes a checkpoint file that describes the point to which the restore has progressed.

This option is really meant for large backups that span several tapes; it lets you restart a restore operation without having to go back to the first tape. However, it can also be useful for restoring disk-based backups.

For differential backups, how is the data determined for those backups?

DCM page contains information about the extent which are changed after the Full backup. Diff. backup process reads information about the changed extents and those extents are added in the differential backup.

What is the meaning of the values in the Type column in backupset table?

• D – Database
• I – Differential database
• L – Log
• F – File or filegroup
• G – Differential file
• P – Partial
• Q – Differential partial

What is Recovery Time Objective (RTO)?

Recovery Time Objective (RTO) is the amount of time which data or hardware is desired to be restored after a data corruption or hardware failure.

What is Recovery Point Objective (RPO)?

Recovery Point Objective (RPO) describes a point in time that data can be restored from. For instance, if there is data corruption, Data loss or unavailability, at what point in time can a valid copy of the data be restored from? RPO is usually measured as minutes, hours, days, weeks etc.

What are the different types of Restore options?

• Restore an entire database.
• Restore part of a database.
• Restore specific files or filegroups.
• Restore specific pages to a database.
• Restore a specific transaction log.

Basic steps to verify backups regularly.

• Check SQL Server error log for backup related entries.
• Check msdb.dbo.backupset table for backup related entries.
• Check the backup existence in the file system.

How to check if your database backups are restorable?

You can use RESTORE VERIFYONLY command to validate the backup.

Syntax:

RESTORE VERIFYONLY FROM DISK = C:\dbrnd.BAK

How you can automate the backup process?

Backups can be automated by using T-SQL script and you can execute and configure this T-SQL script using SQL Job.

You can also configure automated Database Maintenance Plan in which you can configure all different types of backups.

What do you know about the online backup?

In addition to doing backups to your local disks there are several companies that offer online backups via the internet.  Instead of you have to manage your backup files locally these services allow you to backup your databases via the internet and therefore you have an external copy stored outside of your company’s network.

How you consider the recovery model between Full recovery model and Simple recovery model?

If you are dealing with huge amount of data and failure chances are also less, you should use the simple recovery model.

If data failure risk is very high, you should use the full recovery model.

What are the three basic phases for database recovery?

• Analysis
• Redo – rolls forward committed transactions
• Undo – rolls back any incomplete transactions

What is a point in time recovery?

A point in time recovery is restoring a database to a specified date and time. When you have completed a point in time recovery, your database will be in the state it was at the specific date and time you identified when restoring your database. A point in time recovery is a method to recover your database to any point in time since the last database backup.

What do you require for point in time recovery?

In order to perform a point in time recovery you will need to have an entire series of backups (complete, differential, and transaction log backups) up to and/or beyond the point in time in which you want to recover.

I’ve just deleted a table! I know it is in the log. How do I get it back?

If the tables were dropped, ApexSQL Recover can recover them even from databases in the simple recovery model. ApexSQL Recover can recover both table structure and table records.

Another approach is,  You should immediately take a log backup of your database and need to perform a process called a point in time recovery.

What is a Tail-Log Backups?

The tail-log backup captures records on the transaction log that were written since the last transaction log backup. If you’re going to restore a database to the point of failure, then you need to take a tail-log backup before you start the restore operation.

In which situation Tail-Log Backups is not required?

You do not need a tail-log backup if the recovery point is contained in an earlier log backup.

A tail-log backup is unnecessary if you are moving or replacing (overwriting) a database and do not need to restore it to a point of time after its most recent backup.

Why Tail-Log Backups have an incomplete Backup Metadata?

Tail log backups capture the tail of the log even if the database is offline, damaged, or missing data files. This might cause incomplete metadata from the restore information commands and msdb. However, only the metadata is incomplete; the captured log is complete and usable.

Can you take Tail-Log Backup in simple recovery model?

No, you can take Tail-Log backup only with full or bulk-logged recovery models.

In which scenarios, you require a Tail-Log Backup?

If the database is online and you plan to perform a restore operation on the database, begin by backing up the tail of the log.

If a database is offline and fails to start and you need to restore the database, first back up the tail of the log.

If a database is damaged, try to take a tail-log backup by using the WITH CONTINUE_AFTER_ERROR option of the BACKUP statement.

What are the issues you faced in backup and restore process?

• Error 3201 – Cannot open backup device.
• Error 3205 – Too many backup devices specified for backup or restore.
• Error 4305 – an earlier transaction log backup is required.

Can you access the database during a backup operation?

SQL Server backups are an online process; the data stored in SQL Server is highly available during this time. Operations such as INSERT, UPDATE, and DELETE are allowed, as are SELECT statements.

However, operations that would modify the underlying table or file space architecture, such as ALTER DATABASE, ADD FILE, or SHRINKFILE, can’t be done while the backup is running.

What are your steps to prevent the increasing size of Transaction log file?

• Backup the log files and make disk spaces free.
• Moving the log file to another disk.
• Adding a new log file on a different disk.
• Shrinking the log file.

What are the restore options available?

• With Recovery: Database is ready to use, and user can connect to database, user can change data inside database.

• No Recovery: Database is not ready, there are few more backups that have to be applied to this database instance. The User cannot connect to the database because it is in Restoring Status.

• Standby / Read Only: Database is ready to use but database is in Read Only mode, user can connect to database but they cannot change data inside database.

What are the different types of Backups?

• Data backup
• Database backup
• Full backup
• Copy-only backup
• Differential backup
• Log backup
• File backup
• Partial backup

What are the different types of Recovery Model?

• Simple: transaction log backups are not supported by the simple recovery model.
• Full: you can take all data and log full backup.
• Bulk logged: Reduces log space usage by using minimal logging for most bulk operations.

What is LSN ?

Every record in the SQL Server transaction log is uniquely identified by a Log Sequence Number (LSN).

The LSNs are sequential and in the particular ordered, new LSN is always higher than the old LSN.

What is the value of DatabasebackupLSN for the first full backup file?

A DatabaseBackupLSN is a zero and FirstLSN is same as CheckpointLSN.

What is First LSN?

The log sequence number (LSN) of the first transaction in the backup set. Blank for file backups.

What is Last LSN?

The log sequence number (LSN) of the last transaction in the backup set. Blank for file backups.

What is Full LSN?

The log sequence number (LSN) of the most recent full database backup.

How to find LSN information of the Database Backup Files?

SELECT last_log_backup_lsn
FROM sys.database_recovery_status
WHERE database_id = DB_ID();

One scenario, As a DBA you have already created one database maintenances plan to take database full backup, differential backup and transaction log backup. This plan is running in the background as per defined schedule.

Now your client requires one ad-hoc, full database backup so you have taken full database backup for some X reason.

In other side, your defined backup plan is also running and accidently your system crashed.

Now you have to restore your database and you are restoring your database by using full backup which is taken by database maintenance plan.

Next step is to start restoring of differential backup.

But I got an error like, your database LSN are mismatch.

What do you know about this?

Yes, LSN was broken because we have taken one ad-hoc full database backup so there are two solutions.

First, we have to use ad-hoc full database backup as a base full backup.

Second, we have to take this kind of ad-hoc full database using COPY-ONLY option.

What is Copy-Only Backup?

The Copy-Only Backup is similar to Full database backup, it takes full database backup without modifying the DatabaseBackupLSN.

It does not break the chain of differential backups.

T-SQL Script to take Copy-Only Backup.

BACKUP DATABASE Database_Name TO BackupDevice WITH COPY_ONLY

What is your backup retention policy?

Never store databases and backups on the same disks because when a disk failure occurs, then you lose both backups and databases.

Store database backups on both local server and remote server. If your database size is very big the, you can use a local database backups for instant standby restore.

If you are following Agile Software Development Methodology, you should take Sprint wise database backups which help us to track and manage different functionality changes.

Why you require to restore a database?

• Application failure
• Server failure
• Disk failure
• Database failure
• Database corruption
• Research data issue
• Data corruption

What is your suggestion for the SQL Server backup plan?

Establish a full backup schedule either on a multi-day, daily, weekly or monthly basis.

Incorporate differential backups into the plan to increase the available recovery points between full backups. (e.g take after every 3 to 4 hour)

If additional points in time are needed, then consider transaction log backups as a solution to meet a final level of granularity for recovery purposes. (e.g take after every 10 min)

What is your preparation before database restore happen?

• Get the version of the destination server.
• Get the version of the source server on which the backup was created.
• Match the versions of the source and destination servers.
• Ensure exclusive access to the database.

Why database restores fail?

• Unable to gain exclusive use of the database.
• LSN’s are out of sequence so the backups cannot be restored.
• Syntax error such as with the WITH MOVE command.
• Sufficient space not available on drive.
• User may not have sufficient permissions to perform the restore.

Which database contains all types of system tables and do we perform backup and restore for that system tables.

The MSDB database is the database with the backup and restore system tables.

Yes, we can perform the backup and restore operation for the MSDB.

How a differential database backup work?

If data changes on any one of the pages in an extent, a flag is set at the extent level to indicate that the extent must be backed up.

If you have 10 differential database backups, how you restore these all differential database backups?

Not require all 10 differential database backups. First restore last database full backup and restore only last taken differential database.

What are your basic steps to perform database recovery using database backups?

• Restore the most recent full backup with the NORECOVERY clause.
• Restore the most recent differential backup with the NORECOVERY clause.
• Restore all of the subsequent transaction log backups with the NORECOVERY clause, except the last transaction log backup.
• Restore the last transaction log backup with the RECOVERY clause.