Error Description 

OLE DB provider “SQLNCLI” for linked server “MYView” returned message “The transaction manager has disabled its support for remote/network transactions.”.

 Msg 7391, Level 16, State 2, Line 23

 The operation could not be performed because OLE DB provider “SQLNCLI” for linked server “MYView” was unable to begin a distributed transaction.

 Resolution:

1. Check whether DTC is blocked by firewall, if it is blocked by firewall release it.

2. Check or configure DTC to allow network connection as below.

Go to Control Panel ->Administrative Tools -> Component Services -> Expand the Computer Node -> Right click on My Computer) -> Click on Properties -> MS DTC Tab -> Security Configuration

You can use below query to generate DBCC Shrikfile command for data and log file.

Query

select ‘use ‘ + db_name(dbid) +  char(13) + ‘dbcc shrinkfile (‘ + quotename(name,””) + ‘ ,truncateonly)’ from sysaltfiles

Error:  Login failed for user ‘(null)’. Reason: Not associated with a trusted SQL Server connection.

Error clearly state that login is not associated with the trusted connection.

What is trusted connection and what is the advantage of it? Integrated authentication allows for SQL Server to leverage Windows NT authentication to validate SQL Server logon accounts. This allows the user to bypass the standard SQL Server logon process. With this approach, a network user can access a SQL Server database without supplying a separate logon identification or password because SQL Server obtains the user and password information from the Windows NT network security process.

Advantage of this process is that we don’t have to store credential with the connection string.

However sometimes you will see the error above error.

Resolution

1. Change the authentication mode to mixed mode from SSMS or Enterprise Manager

2. Check the user/login is associated with the appropriate SQL login

3. Host is in the same domain or Host machine is network, sometime rebooting of the host machine will resolve this issue.

 DBCC PAGE 

We can use the undocumented DBCC PAGE command to view the page header, data rows, and row offset table for any data page in a database. You have to turn on traceflag 3604 before running this command.  You can also use this command when you find the IO bottleneck and query is waiting Page Latches.

Permission: System Admin rights

Syntax

dbcc page ( {‘dbname’ | dbid}, file number, page number [, print opt={0|1|2|3} ])

 You can pass the below print option parameter as per the requirement

• 0 – print just the page header
• 1 – page header plus per-row hex dumps and a dump of the page slot array (unless it’s a page that doesn’t have one, like allocation bitmaps)
• 2 – page header plus whole page hex dump
• 3 – page header plus detailed per-row interpretation

Trace Flag – 3604 Trace flag 3604 is the most commonly used trace flag. It sends the output of a trace to the client. For example, before you can run DBCC PAGE, which views data page information, you must run this trace flag. 

DBCC traceon(3604)

DBCC PAGE ( {dbid | dbname}, filenum, pagenum [, printopt] [, cache] ) 

The output from DBCC PAGE is divided into four main sections: Buffer, Page Header, Data, and Offset Table (really the Offset Array).

Just a few days back I received an issue regarding disk size is out of space. I have tried to shrink the database using DBCC ShrinkFile but there isn’t any success.

I have follow below steps to resolve this issue and it really works.

I have check the below query for

Select name,log_reuse_wait_desc from sys.databases

1. There was another database which is waiting log backup to release the space
2. There was one database who is waiting for Replication to release the space

Database who is waiting for log backup to release the log space

I have taken the log backup two times and executed the database shrink file command to release the space and it has reclaimed 40GB space from transaction log file.

Database who is waiting for Replication to release the log space

This database is in Simple recovery mode and there isn’t any replication enable on this. I have executed the DBCC OPENTRAN command to see any active transaction. I have executed the DBCC OpenTran and it has provided me the below result.

Oldest active transaction:

    SPID (server process ID): 101

    UID (user ID) : -1

    Name          : INSERT

    LSN           : (999:138204:2)

    Start time    : OCT  13 2009  1:34:47:827PM

    SID           : 0×88d52e4051a71143adee5dc7b6619f8a

Replicated Transaction Information:

        Oldest distributed LSN     : (890:2091888:1)

        Oldest non-distributed LSN : (896:2784855:1)

I don’t know the exact reason what happened internally. But from the output it seems that there is unmark distributed transaction. So I have executed Sp_Repldone command to unmark the LSN

EXEC sp_repldone @xactid = NULL, @xact_segno = NULL, @numtrans = 0,     @time = 0, @reset = 1

 Than I have executed the DBCC ShrinkFile command and it has reclaimed the 400GB space

Problem:

An error has occurred while establishing a connection to the server. When connecting to SQL Server 2005, this failure may be caused by the fact that under the default settings SQL Server does not allow remote connections. (provider: SQL Network Interfaces, error: 28 – Server doesn’t support requested protocol) (Microsoft SQL Server, Error: -1)

Resolution:

Check the below setting at Server Level
1. Check the firewall for any blocking (i.e TCP/IP Port:1433)
2. Check the SQL Server Instance Name, there may be chances of the spelling mistakes
3. May be remote connection is disable. Use the SAC (SQL Server Surface area configuration tool for remote connection)
4. Check the status of SQL Browser Service, it should be running to allow remote connectivity

What are the features we can enable using Surface Area Configuration Tool?

• Ad Hoc Remote Queries
• CLR Integration
• DAC
• Database Mail
• Native XML Web Service
• OLE Automation
• Service Broker
• SQL Mail
• Web Assistant
• XP_cmdshell

During the interview I always like to ask below security questions to DBA. I found that sometimes DBAs are not able to answer these questions.

Question 1: What will you do if you lost rights of your SQL Server instance?

We can use the below options

1. Dedicated Administrator Connection
2. BUILIN\Administrator Group (Incase its rights are not revoked)
3. Final Option is to change the registry value
4. You can change authentication mode via registry 

Question 2: – What is SQL Injection?

SQL Injection is developed where unhandled\unexpected SQL commands are passed to SQL Server in a malicious manner.  It is a problem because unknowingly data can be stolen, deleted, updated, inserted or corrupted. 

Question 3: – What is the Guest user account in SQL Server?  What login is it mapped to it?   

The Guest user account is created by default in all databases and is used when explicit permissions are not granted to access an object.  It is not mapped directly to any login, but can be used by any login.  Depending on your security needs, it may make sense to drop the Guest user account, in all databases except Master and TempDB 

Question 4: – What is the use of BUILTIN\Administrators Group in SQL Server?

Any Windows login in BUILTIN\Administrators group is by default a SQL Server system administrator. This single group can be used to manage administrators from a Windows and SQL Server perspective

Step 1: Open SSMS

Step 2: Connect to desire Server and right click on the server (for i.e. sqldbpool) and Select properties

Step 3: Click on memory tab and configure Min and Max memory

Like SQL Server 2005, SQL Server 2008 supports clustering using both the Standard and Enterprise editions. The Standard edition supports a two-node cluster, and the Enterprise edition supports the maximum number of nodes that the OS supports 

The biggest changes in SQL Server 2008 cluster is that you can now use DHCP for clustering and use IP addresses from different subnets for each side of the cluster. The ability to use IP addresses from different subnets is most useful for creating multisite clusters, called geographically distributed clusters.

SQL Server Cluster Installation

Step 1: I hope you had done with all the pre-requisites required by cluster.If you’re installing SQL Server 2008 in a cluster on Windows 2003, you’ll need to download and install the hotfix specified in the Microsoft article at http://support.microsoft.com/kb/937444  before you can install SQL Server 2008.

Note: Installation of above hotfix requires a reboot, so you have to cancel out of the installer at this point and restart the process after installing that hotfix on all your cluster nodes.

Step 2: Open SQL Server 2008 installation executable file from your CD\DVD\Shared location

Double click on installation.exe and you will find the below screen. Now select New SQL Server Failover Cluster installation option highlighted as in below image. (Note: For standalone installation we have to select standalone option)

Step 3: Once you have selected Step 2 option, installation will check for setup support rules to identify the problem. If it is failed due to any reason, you have to correct the issue. Please find the below screen shot. If it passed click on OK command button.

Step 4: Installation wizard will install the setup support files, click on Install command button

Step 5: This step will walk you through all the required information as below. Click on Next button

1. Product Key

2. Licence Terms

3. Feature Selection

4. Disk Space Reuirements

5. Error and Usage Reporting

6. Cluster instllation Rules

7. Ready to install

8. Installation Progress

Step 6: Enter Product Key or It will take automatically. See the below image for it.

Step 7: Select required features, which you want install.

Step 8: Specify the Network Name/Virtual Name for SQL Server to failover. As we are installing Active-Passive cluster we have to specify one virtual/network name. (Note: For Active-Active clustering you have specify different network names as per the number of nodes)

Step 9: SQL Server will review the disk space requirement for the features you have selected

Step 10: This step will create a new cluster resource group for your SQL server failover. Please see the note in the image.

Step 11: Select shared cluster disk resources for your SQL Server failover cluster

Step 12: Here you have to select network resources for your SQL Server failover cluster. You have to add IP address as well.

Step 13: Here you have to specify the service account for SQL Server services. It is a best practice always keeps SQL Services in cluster in manual mode

Step 14: Specify the authentication more and SA password in account provisioning tab, configure the location of the data files, log files, temp database in data directories tab and enable file stream as per the requirement

Step 15 

Step 14: Specify the authentication more and SA password in account provisioning tab, configure the location of the data files, log files, temp database in data directories tab and enable file stream as per the requirement

Step 15: Select check boxes as per your requirement, I haven’t checked any option. Proceed with the next button

Step 16: Installation wizard will check the cluster installation rules, please correct if you found any failure and proceed with the next button

Step 17: Now your SQL Server cluster is ready to install. Click on Install button

Step 18: Apply the required Service Pack/Patch and reboot the server

Step 19: Once installation is done on this node, we have to proceed with the installation of SQL Server on the other cluster nodes. SQL Server 2005 was the last edition of SQL Server to automatically install SQL Server on all nodes at once.  Beginning with SQL Server 2008, we must manually install and patch each cluster node individually. This process allows for less downtime as we are patching the cluster or upgrading your cluster from SQL Server 2005 to SQL Server 2008.

Step 20 Installation on the other nodes is similar to installing on the first node except that we have select the Add Node to a SQL Server failover cluster option from the initial menu. The same software requirements apply to the other nodes in the cluster, so the installer will handle the verification and installation of these components as well.

Because most of the settings are picked up from the other node(s) in the cluster that already have SQL Server installed on them, the process of adding a node to the cluster is bit shorter than installing on the first node 

Step 20 Installation on the other nodes is similar to installing on the first node except that we have select the Add Node to a SQL Server failover cluster option from the initial menu. The same software requirements apply to the other nodes in the cluster, so the installer will handle the verification and installation of these components as well.

Because most of the settings are picked up from the other node(s) in the cluster that already have SQL Server installed on them, the process of adding a node to the cluster is bit shorter than installing on the first node