What is the difference between database upgradation and database migration

Today, let us see about the difference between upgrade and migration.

First of all let me give you a brief definition of both

UPGRADE:

Process of changing version of database from lower release to major release is called UPGRADE. For example, moving from 10.2.0.1 to 11.2.0.1. 10.2.0.4 to 11.2.0.3, 9.2.0.8 to 10.2.0.5 etc

Usually, we will upgrade the database without changing the physical server. Means, in the existing server itself we will upgrade the DB to new release.

Reasons for upgrade:

1. To continue support with Oracle (because Oracle will not support if you have a license of unspported version. for example, Oracle stopped support for 10g now, so if you have 10g database you cannot get any help from Oracle support to raise SR’s, to fix any bugs etc)

2. There is a serious bug which got fixed only in new release.

3. Client has license for new release

4. Application will work better with new version of database etc

MIGRATION:

Process of changing OS platform for a database server. For example, moving a database from Solaris server to Linux server, windows to Solaris etc.

Ideally in most of the migration projects, there will be a change in physical server i.e If we have a server with Solaris 5.10 and now client decided to move to latest server with RHEL 6, we call it as migration.

Some of the reasons why client need this…

1. the existing server became old and doesn’t have expanding capability (like we cannot extend memory, disk space or CPU etc)

2. existing OS license got expired and client want now to use cheaper OS (like Linux)

3. moving from one data center to another to reduce cost of maintenance etc

Many a times, migration also involves upgrade. usually, out of 100% migration projects, 80-90% will involve the task for upgrade database along with migration.

For example, there is a 10.2.0.4 database running on X server with Solaris 5.10 and client decided to move to 11.2.0.3 database on Y server with RHEL 6. In this case, it involves both migration (because you are changing the platform) and upgrade (because database release is changing).

With this, I hope I have explained little bit about upgrade Vs migrate.