Few content are taken from Microsoft blogs:
Step by step process of migrating legacy Public folder to Exchange 2013 modern public folder:
Once we know how to configure Modern public folders and want to migrate it from Exchange 2007/2010 Public Folders to Exchange 2013. Here are few documentation on how to do this and is ready to get started.
Complete following tasks:
Verify that we can start the Migration:
Gather the data for the migration:
* Note: We are using a Mailbox Size of 500kb here so that it put the folders in multiple Mailboxes. Powershell Understand KB, MB, GB so for production environments you could use "25GB" for a 25 Gigabyte Mailbox.
Create the Public Folder Mailboxes:
Start the Migration:
Monitor the Migration:
Lock the 2010 Legacy Folders (Use workaround):
Complete the Migration:
*Note: There are four phases while completing the migration. Once migration reach to 95 % it will lock public folder access to end users on Exchange 2010/2007. After reaching to 95 % it will go with below phases:
Lock down the public folders on the legacy Exchange server for final migration (downtime required):
The amount of downtime required depends on how much new content was generated since the migration reached the AutoSuspended state. If a long time has passed between the migration request reaching an AutoSuspended state and when you can finalization the migration, we recommend that you run the following command so you can synchronize the changes made since the original synchronization. This will reduce the amount of downtime required to finalize the migration.
Note: If your organization has multiple public folder databases, you’ll need to wait until public folder replication is complete to confirm that all public folder databases have picked up the PublicFoldersLockedForMigration flag and any pending changes users recently made to folders have converged across the organization. This may take several hours.
Finalize the public folder migration (downtime required):
By default, when you run the Set-PublicFolderMigrationRequest cmdlet, it won’t complete until you remove the PreventCompletion flag and resume the migration request.
Test and unlock the public folder migration:
After you finalize the public folder migration, you should run the following test to make sure that the migration was successful. This allows you to test the migrated public folder hierarchy before you switch to using Exchange 2013 public folders.
a) View the hierarchy.
b) Check permissions.
c) Create and delete public folders.
d) Post content to and delete content from a public folder.
Microsoft article: http://technet.microsoft.com/en-us/library/jj150486(v=exchg.150).aspx