|Message:||%1 (%2) %3 The database engine is rejecting update operations due to low free disk space on the log disk.|
This event is usually seen with ESE Event ID 482. Event ID 482 will precede Event ID 428, and indicates a failure to write to a file.
Check the available disk space on the drive you are using. If necessary, delete some files to free disk space. If the accompanying Event ID 482 indicates a failure to write to disk because of any other error, then this may not be a disk space issue.
For more information, review Microsoft Exchange Server Analyzer article ESE 428 (0xfffff8f0): Insufficient Free Space Remaining on Transaction Log Drive.