Before planning a SharePoint upgrade, certainkey points carry importance for a successful implementation. First of all, detecting possible issues about the deployment is of core importance in order to meet the upgrade schedule, then how much an organization requires downtime for carrying out day to day operations or is there any need for upgrading farm or server configurations? In addition, sometimescustomizations are also required on the SharePoint 2010 farm as well. In this regard, the under mentioned best practices if adopted precisely can lead to a smooth upgrade. Run a Pre-Upgrade Check Get the status of your SharePoint sites and servers before a SharePoint 2010 upgrade. Server administrator can solve any potential issues for upgrade with a Pre-Upgrade check. Pre-upgrade checker is available with Office SharePoint Server 2007 Service Pack 2(updated version) and October 2009 Cumulative Update for Windows SharePoint Services 3.0 (updated version). Is Your Environment Fully Functional? As, upgrade does not resolve any issues that exist in your environment so it is recommended to unextend your web applications which are not being used in the Internet Information Services (IIS) beforehand because SharePoint 2010 will try to upgrade the application even if it does not exist which will result in an upgrade failure. Update Servers to Service Pack 2 If you want to run an in-place or database-attach upgrade you must change your existing environment to Service Pack 2 of Microsoft Office SharePoint Server 2007.Pre-upgrade checker has been improved in the October 2009 Cumulative Update so it will be better to install for achieving a simplified upgrade. Upgrade OS to 64-bit Servers Migrate to 64-bit version of Windows Server 2008 R2 or Windows Server 2008 with SP2 before trying an In-place upgrade. For SQL server users, they should migrate to 64-bit version of Microsoft SQL Server 2008 R2 and SQL Server 2008 with Service Pack 1 (SP1) with Cumulative Update 2. But if, you are using SQL Server 2005, then upgrade to SP3 and Cumulative Update 3. For carrying out an in-place upgrade, yourexisting system should be running on a supported OS. An important point to consider is not to merge your upgrade process with these operations. Estimate the Storage Space and Time required for upgrade You need 64-bit hardware and 64 bit versions of the Operating System as well as Microsoft SQL Server. Either for an in-place or database-attach upgrade process, you need toupdate to Office SharePoint Server 2007 Service Pack 2 to carry out the upgrade process. It is important to know the storage space required and the time needed for an upgrade process. Conducting a trial upgrade can help estimate the space and time required for any such upgrade. Perform a Full Backup of the Farm It is recommended to back up the Microsoft Office SharePoint Server 2007 environment before commencing with the upgrade process. You should also back up all customizations if you have deployed them. You must test these backupsso that you will be able to recover if there is some kind of hardware failure. Make Your Environment Effectual Query throttling on large lists and changes in limits of site collection per content database are some new changes that have been introduced in SharePoint Server 2010. The new limits on site collections include (5000 warning and 15000 limit to 2000 warning and 5000 limit. Office SharePoint Server 2007 environment must be optimized in order to meetthese limits. Add server to farms either before or after completing the upgrade process The configuration database is upgraded when SharePoint Products Configuration is run. It contains the list of serversin a farm.Servers added to a farm after running the configuration wizard do not appear in the database so it is suggested to add servers to farms after or before running an upgrade. Set Databases to READ ONLY mode While adopting a database attach approach, you may set the original databases to a read only mode to enable users to continue to access their data in a read only form. Review Upgrade Status page and Upgrade Logs You can always deal withissuesby looking at the Upgrade Status Page and Upgrade Logs.TheUpgrade Page shows the details regarding the upgrade process while the upgrade log shows possible warnings or errors.After the completion of upgrade process, make sure to test and verify all the sites.