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Troubleshoot Blocking

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 Troubleshooting Blocking 

What is blocking? Blocking occurs when one connection to SQL Server locks one or more records, and a second connection to SQL Server requires a conflicting lock type on the record or records locked by the first connection. This causes the second connection to wait until the first connection releases its locks. By default, a connection will wait an unlimited amount of time for the blocking lock to go away. Blocking is not the same thing as a deadlock. 

How to avoid blocking

  1. Keep transaction as short as possible
  2. Use locking hints
  3. Follow best practices for Database Maintenance regularly
  4. Improve Query performance so it executes in seconds

Note:

By default, blocking locks do not time out.You can set blocking timeout using below SET statement.

SET LOCK_TIMEOUT timeoutPeriod

 How to find blocking

  1. SP_WHO2 and find the blkby column from output for blocking details
  2. Use SP_Lock to find out lock acquired by blocking query
  3. Select * from sysprocesses where blocked <>0
  4. You can get the blocking SQL Statement using DBCC INPUTBUFFER(SPID)
  5. SP_WHO2 SPID

kernel udopen: operating system error 2 in SQL Server 6.5

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One of my blog reader encountered below error, I have given him the below solution which has resolved this issue.

Error: (SQL Server 6.5)

2009/07/15 19:42:26.89 spid1    Activating disk ‘ITEMPRICE_DATA1’

2009/07/15 19:42:26.89 kernel   udopen: operating system error 2(The system cannot find the file specified.) during the creation/opening of physical device F:\DATA\ITEMPRICE_DATA1.DAT

2009/07/15 19:42:26.89 kernel   udactivate (primary): failed to open device F:\DATA\ITEMPRICE_DATA1.DAT for vdn 42

2009/07/15 19:42:26.89 spid1    Activating disk ‘ITEMPRICE_DATA2’

2009/07/15 19:42:26.89 kernel   udopen: operating system error 2(The system cannot find the file specified.) during the creation/opening of physical device F:\DATA\ITEMPRICE_DATA2.DAT

2009/07/15 19:42:26.89 kernel   udactivate (primary): failed to open device F:\DATA\ITEMPRICE_DATA2.DAT for vdn 43

Solution

1) Rebuilding System Databases by running setup again from the SQL Server Install CD and do a rebuild master.

2) If it’s a 6.5 box, you can go to the console and view the sa password in the registry. run regedit from the console:
HKEY_CURRENT_USER
Software
Microsoft
MSSQLServer
SQLEW
Registered
SQL 6.5
ServerName

3) Check for the directory whether F:\ has Data directory or not

4) Check if the drive was corrupted

4) Check the SQL Server Service running on which account, check the permission of that account

5) http://support.microsoft.com/kb/180500

6) http://support.microsoft.com/kb/236989

7) Go through BOL on SQL Server 6.5 startup parameters

8) Try to login using command prompt and execute Sp_Resetstatus, DBCC CheckDB etc

sqlservr -c -f -T3608 -T4022

9) Check all the databases status from sysdatabases

 

How to find database restore history from MSDB?

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MSDB database is used by SQL Server Agent for scheduling alerts and jobs and by other features such as Service Broker and Database Mail. Again SQL Server is using MSDB for storing the history of backup, restore, log-shipping details and more…

You can query the MSDB as below to get the details about the SQL Server restore history.

SELECT TOP 10 *
FROM restorehistory WITH (nolock)WHERE (destination_database_name = 'Database Name')ORDER BY restore_date DESC
All Databases

SELECT TOP 10 * FROM restorehistory WITH (nolock)ORDER BY restore_date DESC

How to improve communication skills & Support Service

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As DBA comes under the support industry, it is extremely important for DBAs to improve communication skills. As we are working production servers and backend, it is extremely important for us to communicate properly. 

  • Please take care of the below points to improve your written communication skill. 
  •  When you reply all, make sure to move names from TO to CC and CC to TO list according to whom you are writing emails
  • Be concise and to the point. Use simple English.
  • Avoid the use of slang words/abbreviations
  • Use proper spelling, grammar & punctuation
  • Do not write in CAPITALS. CAPITALS indicate that we are shouting.
  • Numbers should be expressed as words when the number is less than 10 or is used to start a sentence (example: Ten years ago, my brother and I…). The number 10, or anything greater than 10, should be expressed as a figure (example: My brother has 13 Matchbox cars.)
  • You should just mention the name instead of Hi Jugal.As we are working as support team, use `We` instead of `I`. For example; Jugal instead of Hi Jugal
  • You should change the text in the Subject line during reply emails if it is not relevant.
  • If you are asking for something in the email, you should ask them first and then mention why you need that.
  • Don’t write open ended email to user
  • If you are not sure for any support request, please ask end user for more inputs on particular request.
  • Inform your team regarding any conversation with client through chat or voice call
  • Update your work log every day
  • If you are not sure for any resolution steps, discuss it with your team and then provide it to client
  • When sending large attachments, always “zip” or compress them before sending.
  • Always include subject in your mail body.
  • Don’t send email to any account using your client account
  • Discuss as much as possible with your client
  • Grab as much as possible knowledge of the client process/environment