Mailbox archives can be stored in any database on the Exchange server. An ‘Archive’ Database is just like any other Exchange Database, nothing special. That said, I advice you create a dedicated Database for the archive and name it something like “Archive 01”. Note: depending on your environment you may opt to store the Archive DB on less expensive storage than your primary production databases.
Here is the command to create the Archive Database using Exchange Management Shell:
New-MailboxDatabase -Name “Archive01” -EdbFilePath “M:\ExchangeDB\Archive01\Archive01.edb” -logFolderPath “L:\ExchangeDB\Archive01″
On my installs I generally create a volume M for databases and a volume L for transaction logs. Use your applicable paths and drive letters.
Here are steps to enable archiving for a users mailbox