This script helps us to find out which are the largest log files in size so we can try to shrink them to the minimum size.
This script dynamically changes the Recovery Model to simple and then shrinks the file; then it makes the Recovery Model the orignal one.
DECLARE @tbl TABLE
(
ID INT IDENTITY(1,1),
DBNAME NVARCHAR(1000),
[FileName] NVARCHAR(1000)
)
INSERT INTO @tbl
SELECT DB_NAME(DbID),st.NAme from sys.sysaltfiles ST INNER JOIN Sys.databases SB on ST.dbid = sb.database_id where Size > 100000 AND FileName LIKE '%ldf' and sb.state = 0
DECLARE @MinID INT , @MaxID INT,@DBName NVARCHAR(1000),@FileName NVARCHAR(1000),@RecoveryModel NVARCHAR(1000),@SQL NVARCHAR(MAX)
SELECT @MinID = MIN(ID),@MaxID = MAX(ID) FROM @tbl
WHILE(@MinID <=@MaxID)
BEGIN
SELECT @DBName = DBNAME,@FileName=[FileName] FROM @tbl where ID = @MinID
SELECT@RecoveryModel = recovery_model_desc FROM sys.databases where name = @DBName
SELECT@SQL= N'USE ['+ @DBName+']'+CHAR(10)+CHAR(10)
+CASE WHEN @RecoveryModel <> N'SIMPLE' THEN N'ALTER DATABASE ['+@DBName+'] SET RECOVERY SIMPLE WITH NO_WAIT'ELSE N''END+CHAR(10)+
+N'DBCC SHRINKFILE('+@FileName+',1)'+CHAR(10)
+CASE WHEN @RecoveryModel <> N'SIMPLE' THEN N'ALTER DATABASE ['+@DBName+'] SET RECOVERY '+@RecoveryModel+N' WITH NO_WAIT'+CHAR(10) ELSE N'' END
+CHAR(10)
PRINT @SQL
EXEC SP_EXECUTESQL @SQL
SELECT @MinID = @MinID +1
END 
This metric measures the percentage of free space for transaction log files (LDF files). You’ll find this useful if your SQL Server has limited capacity, so you need to maximize existing disk space utilization by minimizing unused space. It will also alert you if the amount of free space drops below the specified thresholds.
2013-09-17
3,155 reads
Performs a checkpoint or a transaction log backup followed by a DBCC SHRINKFILE on the transaction log to the target percentage specified relative to the total data file(s) size.
2009-09-23 (first published: 2009-08-27)
2,484 reads