https://technet.microsoft.com/en-us/library/ee633490(v=exchg.141).aspx
But this will not work with Exchange 2013
Instead, yo need to use:
Enable-Mailbox -ArchiveGuid MailboxGuidHere -ArchiveDatabase DatabaseNameHere -Identity MailboxNameHere
Enable-Mailbox -ArchiveGuid MailboxGuidHere -ArchiveDatabase DatabaseNameHere -Identity MailboxNameHere