Copy Queue Length in Exchange 2013

The copy queue length indicates how many transaction logs are waiting to be copied from one mailbox database to it's replication partner. Typically availability of bandwidth could induce such a scenerio like this - by identifying it early you should be able to prevent any larger scale issues arising.

In order to view the copy queue legnth on the mailbox server you can use EMS:

Get-MailboxServer | Get-MailboxDatabaseCopyStatus | Sort-Object Copyqueuelength