Allocating space on a new device

The tempdb Properties dialog has the following fields:

Add – Allows you to add more space.
Edit – Allows you to modify the current space allocation.
Remove – Remove an allocation.
Move Log – Moves the transaction log of a database with log and data on the same device to a separate database device. As described in sp_logdevice .

For example, if a database has 2 devices master and device1, both containing data and log. If you select device1 and click Move Log, the Future Allocation value for device1 will become Log. Before sp_logdevice can be issued, the database has to be put into single user mode, which can be done on Options page.
Properties opens the properties of the selected device.

Expanding a database by allocating space on a new device

Select the database icon, then select File | Properties.
Select the Devices tab.
Click Add. The Available Devices dialog box opens.
From the list of available devices, select the device on which you want to allocate space to this database.
Specify whether the device is for Data or for Transaction Log.
In the Size box, specify the amount of space on the selected device that you want to allocate to this database.
Click OK.

When the original device is full, any additional database expansion takes place on the new device you specified.