What is the difference between database server and database instance?

[Anshu_Anand_]

Dear All,

1. Can anyone explain difference between Database instance and database server

2. How database servers are discovered. i know about database instances but database servers i have no clue.

 

[DirkRedeker]

HI

A Database Server is normally a (virtual) machine, running ONE or more INSTANCES of a database service.

YOu can have machine A with Instances X, Y, Z, and

another machine with only ONE instance, if it is a Database Server.

Anyhow, every Maschine should have (at least) ONE Instance.

Typically, an INSTANCE often runs as a separate Service on that Server machine.

Furthermore, any Instances can (normally) handle any number of databases below.

Instances normally do NOT share databases and have unique access points (e.g. IP/Port number combinations at access).

Let me know, if that answers your question, and mark my answer as correct and helpful.

BR

Dirk

[DirkRedeker]

Hi

After all, is your question answered?

If you like, mark my answer as correct to close this thread.

Thanks & BR

Dirk

[Ashutosh Munot1]

Hi,

1) DB instance vs DB Server

In just about all DB engines - and not just SQL Server - the differences would be:

• An instance is an actual installation of the database software on a particular machine. An instance typically would have its own IP address and port combination exclusively for its use that would allow client applications to connect to it and access data managed by the instance.
• A database in most SQL RDBMS products is a Namespace of tables. Instances usually can support multiple databases, with a table uniquely identified on an individual instance using <dbname>.<tablename>. However, most applications specify a “default” database when they connect to the database instance, which allows a simple <tablename> reference in a SQL query to be unambiguous.

Many RDBMSs allow distinct and separate storage of particular databases, as well as separate configurations and other runtime settings, user permissions, etc.

-

The terms instance and database are closely related, but don't refer to the same thing.

The database is the set of files where application data (the reason for a database) and meta data is stored.

An instance is the software (and memory) that Oracle uses to manipulate the data in the database. In order for the instance to be able to manipulate that data, the instance must open the database. A database can be opened (or mounted) by more than one instance, however, an instance can open at most one database.

2) We need Applicative credentials to discover this instance and database servers.

Thanks,
Ashutosh

[doug_schulze]

It's important to note that Service now Discovery doesn't and never has populated 'Database servers' those are from the first days of our CMDB before Discovery was born.  We do discover and populate the database instances, these will have a relationship to the servers that run them.