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Sunday, 13 December 2015

What is meant by Instance in SQL Server 2008 R2? How many type of instances available ?


Instance : 
                  Instance is a copy of SQL-Server which runs in a system either with same version or different version .

                  SQL Server supports up to a maximum of 50 (based on edition) instances .

                   For more details about versions click here .
                   For more details about editions click here .

                   Instance can be of 2 types


a. Default Instance :
                                 It is a copy of SQL Server which is created with the same name of the system name .
                                 A system can contain only one default instance .
                                 The services of the default instance will be displayed as
                                  service name (MSSQLSERVER)

b. Named Instance : 
                                It is a copy of SQL Server which is created by a user provided name .
                                A system can contain upto a maximum of 49 /50 no of named instances,
                                The services of the named instance is displayed as
                                service name (instance name)

Advantages of Instances :

  a. Allows to maintain multiple copies
  b. Allows to separate the environments such as dev / test / prod.
  c. Allows to differentiate the user permissions across the instances.

Directory Structure of Instances :

  For every instance a separate folder will be created .

<drive>:\Program Files \Microsoft SQL Server \MSSQL.N (Version No) \MSSQL

..... \Backup : Default location of the backup file for that instance .
..... \ Binn : Contains all the .dll and .exe files of that instance .
..... \ Data : Default location of the data file and log files of that instance .
..... \ FTData : Contains the script files which are used to connect with FTP Server .
..... \ Install : Contains the installation scripts .
..... \ Jobs : Default location of the jobs .
..... \ LOG : Default location of the error log file which contains the startup steps .
..... \ repldata: Default location of the snapshot .
..... \Upgrade : Contains the scripts for up-gradation .

             
        

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