Before planning a SharePoint upgrade, certain key 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, 
sometimes customizations 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 un extend 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, your existing 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 to update 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 backups so 
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 meet these 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 servers in 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 with issues by looking at the Upgrade Status Page and 
Upgrade Logs. The Upgrade 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. 
Summary:
Upgrade's best performance relies upon certain special measures and if these 
taken properly then you can definitely conduct a perfect upgrade without a 
failure.It is suggested to find out about possible issues that can occur during 
an upgrade with a pre-upgrade check. Similarly, you need to delete web 
applications which are not in use and the existing environment must be changed 
to Microsoft Office SharePoint Server 2007 Service Pack 2.You need to upgrade 
your operating system to 64-bit server and also require information regarding 
the time required to complete an upgrade and about the storage space. You must 
backup all customizations and farms and optimize your environment to meet the 
limits set for new site collections. You may add servers to farms after or 
before the upgrade and observe the details regarding the upgrade process and any 
warnings. Planning before an upgrade is critically essential because it is the 
ultimate way of commencing a smooth upgrade.
Related Links:
SharePoint
Migration || SharePoint
Upgrade