What are the different Types of Upgrade method used in Sharepoint 2010

Before you run any process to upgrade from Microsoft Office SharePoint Server 2007 to Microsoft SharePoint Server 2010, you have to determine which upgrade approach to take.

Use the information in this article to help compare the pros and cons for each approach and to review information about special cases that might influence your approach

Approach	Description	Pros	Cons
In-place upgrade	You can install SharePoint Server 2010 on the same hardware. You can also upgrade the content and settings in the server farm as part of a single process.	Farm-wide settings are preserved and upgraded. Customizations are available in the environment after the upgrade, although manual steps may be required to upgrade or rework them.	Servers and farms are offline while the upgrade is in progress. The upgrade proceeds continuously. Consequently, you must allocate enough time for all content to be upgraded in sequence.
Database attach upgrade	You can upgrade the content for the environment on a separate farm. The result is that you do not upgrade any of the services or farm settings. You can upgrade the databases in any order and upgrade several databases at the same time. While each database is being upgraded, the content in that database is not available to users.	You can upgrade multiple content databases at the same time, which results in faster upgrade times overall than an in-place upgrade. You can use a database attach upgrade to combine multiple farms into one farm.	The server and farm settings are not upgraded. You must manually transfer settings that you want to preserve from the old farm to the new farm. Any customizations must also be transferred to the new farm manually. Any missing customizations may cause unintended losses of functionality or user experience issues. Copying databases over a network takes time and bandwidth. You must plan for that. You need direct access to the database servers.