How to: Increase the Size of Transaction Log Files
You can expand your transaction log by increasing the size of one or more of its constituent files.
You must always make a backup of the database before you expand it. For more information, see Create a Full Database Backup (SQL Server).
To increase the size of a transaction log file
In the development environment, on the File menu, choose Database, and then choose Alter. The Alter Database window opens.
Choose the Transaction Log Files tab.
Select the transaction log file that you want to expand.
In the Size (MB) field, enter the new size.
If the Unrestricted Growth option is not selected and the transaction log has grown to its maximum size, then you can either select the Unrestricted Growth option or increase the maximum size of one of the transaction log files.
(optional) To increase the maximum size of a data file, in the Maximum Size (MB) field, enter the new maximum size.