By default an Exchange Hub Transport Server has a queue placed in the following location, if you installed Exchange on the C-partition:
C:Program FilesMicrosoftExchange ServerTransportRolesdataQueue
Because this can cause problems if your queue fills up and the system drive has no empty space, it’s wise to change the default queue to a different location. First create a directory on a different drive. In this example we change the directory to : D:ExchangeQueueDB
You can then change the queue location of the queue database by changing the EdgeTransport.exe.config file. (location: C:Program FilesMicrosoftExchange ServerBin)
Open the .config file with notepad and change the following key:
<add key=”QueueDatabasePath” value = “D:ExchangeQueueDB” />
Also relocate the transaction logging location for the queue database. Create a directory for the transaction logfiles. In this example we use : D:ExchangeQueueLogs
Change the following key in the .config file :
<add key=”QueueDatabaseLoggingPath” value = “D:ExchangeQueueLogs” />
After you changed the values, save the file. This will not have affect on Exchange yet. You must first restart the Microsoft Exchange Transport service.
For more information: Technet Article