Hi all,

I have always been confusing about the definition of
Node and Instance in DB2.

Does a node means a physical server that host a DB2?
Does an instance refers to an instance hosted within a node?

Could all you guys help?

MUCH THANKS
ME

It's all in the manuals.

Whenever a local database is created the following directory structure is created:

1.0 directory path
1.1 instance name
1.1.1 nodexxxx
1.1.1.1 database directory 1
1.1.1.2 database directory 2
{other syscatspace, tempsacpe1 and userspace1 sms stuff}
{files needed for database recovery and bookkeeping tasks}

The node directory contains info regarding how and where remote systems or instances can be found as well

In DB2 LUW, when cataloging a node, it is a combination of the physical node (server) and the instance.

The term node has other meanings in other contexts, especially in relation to parallel database configuration. A logical node may mean a partition, and a physical node may mean a server (which can have one or more logical partitions per physical node).

Hi all,

thanks for all your help but it just gets me more confused. How about we
first disregard the issue of partitioned database first in defining node and instance.

MUCH MUCH THANKS
ME

In DB2 LUW, when cataloging a node, it is a combination of the physical node (server) and the instance.

Take this as you are a client connecting to a server, so you sees a server(database host) as node providing you information about the instance and the database that is under that instance.so you catalog that node and starts taking to that database under that instance.
So any times you want to interface to that database , you must go through that instance(that has its own service name/port that is using to listen to the client).

The client also has its own instance, that provide you code/libraries to do all type of work as a client.

Now you are at machine(local) that hosts a database,so you create a instance(infact a instance is nothing but links to various libraries of the same db2 code and various binaries).
so if you want to connect to an instance you attached to it(attached is nothing more than attaching to shared structure that a running instance will have provided through its ipc daemon/listener).
Once you attached to an instance, you ask that instance to connect me to that database(infact every local database is automatically catalog during the creation).

Now in db2 terminology when you are at the local machines or mutiple machines, you can create partitions that are spread across mutiple physcial machines or as logical partitions at the same machine.These are all database partitions that are sharing the same instance and all the other things are unshared.In version 7 or earliar this database partition was known as node partition(infact all the commands the has node clause also work in V8)