This command help you to migrate a mailbox in other DB, from PS.
To move user@domain.com to Database and archive in DataBaseArchiving:
Get-Mailbox user@domain.com | New-MoveRequest -TargetDatabase “DataBase” -BadItemLimit unlimited -AcceptLargeDataLoss:$true -SuspendWhenReadyToComplete:$true -ArchiveTargetDatabase “DataBaseArchiving”
This command help you to view all the mailbox move:
Get-MoveRequest | Get-MoveRequestStatistics
This command help you to del a specific mailbox move:
Remove-MoveRequest user@domain.com