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Wednesday, 10 February 2016

SQL Server DBA Interview question and answers Part 5

1. How SQL Server finds the modified extents for taking differential backups ?

All modifications are recorded in differential change backup page after full backup i.e SQL Server finds the modified extents by using DCM .

2.  What is meant by backup retention period ?

Backup retention period means how many days of backups are maintained in disk / tape . After retention period the existing old backups will be delted .

4. What are main differences are between Disk and Tape ?

Disk : Disk is fast and lives less life . Cost is more and it will be mainly used for online .

Tape : Tape is slow and lives more life . Cost is less and It will be mainly used for offline .

5.  What is the user of Lite Speed third party backup tool ?

Lite Speed 5.0 introduced by Quest Software . The following benefits will get with lite speed .

1. Faster than SQL Server backup .
2. Size can reduce up to 60%.
3. Can secure with encryption .
4. Reduce the load on SQL Server .

5. In which edition On-Line restoration is possible ?

On-Line restoration is possible only in Enterprise edition .

6. What is point-in-time restore and use of that ?

Point-in-time restore is used to restore a database to a particular time just before a failure has occured or before corrupt data .
STOPAT option is used to restore a database to specific time .-

7. What is Restore Strategy ?

1. First Restore recent full backup  with No-Recovery.
2. Then restore last diff . backup with No-Recovery.
3. Then restore all transaction log backups since recent full / diff backups with Recovery .

8. What are permissions required for Log shipping ?

We must have sysadmin permission on each server instance to configure Log shipping .

9. In Log shipping which recovery models can we used ?

We can use either Full or Bulk - Logged recovery models for Log shipping .

10. What are the errors occurred in Log shipping ?

There are two errors occurred during Log shipping .

1. 14420 : This error occurs when the backup job fails .
2. 14421 : This error occurs when the restoring job fails .

11. How to failover secondary server , when the primary server fails in Log shipping ?

If the Primary Server will become un-available do the following steps .

1. Perform one last T.Log backup in the primary server if possible.
2. Disable Log Shipping Jobs.
3. Restore if any backups are not applied at secondary server WITH NO RECOVERY.
4. Restore tail log backup WITH RECOVERY.
5. Remove Log shipping configuration from Primary Server.
6. Select any one of secondary server available to the users by bring into on-line with alter database database name set online
7. Right click on primary database and generate scripts for users and logins.
8. Then move the script to secondary server to create users and logins .
9. Re configure log shipping from new server i.e secondary server.

12. What is Lock escalation ?

Lock escalation is the process of converting a lot of low level locks like row locks , page locks into higher level locks like table locks .

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