02 September 2013

Percentage of used log space

by Paul Millar

45,219 0 Storage

This metric measures the percentage of free space for transaction log files (LDF files). It will also alert you if the amount of free space drops below the specified thresholds.

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If you are using Redgate’s SQL Server monitoring tool, Redgate Monitor, you can instantly install and run this metric on your servers.

This metric measures the percentage of used 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 percentage of used space exceeds the specified thresholds.

It is best practice to pre-allocate the size of the transaction log file whenever you create a new database. This reduces or eliminates the need for autogrowth, which may lead to physical file fragmentation. The size of the file will depend on the number of transactions you expect, and how often you intend to backup the transaction log.

For information on managing your transaction log, see Understanding Logging and Recovery in SQL Server. For details of how to shrink the size of your transaction log, see Recover from a full transaction log in a SQL Server database.

This metric can be used in conjunction with virtual log file monitoring, particularly if you’re using log reader for replication.

Metric definition

Name

Percentage of used log space

Description

This metric measures the percentage of used space for transaction log files (LDF files).

The T-SQL query that will collect data


		
			
			
Transact-SQL
			
			-- create result holder
DECLARE	@result TABLE
	(
	  [Database_Name] VARCHAR(150) ,
	  [Log_Size] FLOAT ,
	  [Log_Space] FLOAT ,
	  [Status] VARCHAR(100)
	) 

INSERT	INTO @result
		EXEC ( 'DBCC sqlperf(LOGSPACE) WITH NO_INFOMSGS'
			)

-- only return for the DB in context, rounding it 
SELECT	ROUND([Log_Space], 2)
FROM	@result
WHERE	[Database_Name] = DB_NAME()
			
				
					
				
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						-- create result holder
DECLARE	@result TABLE
	(
	  [Database_Name] VARCHAR(150) ,
	  [Log_Size] FLOAT ,
	  [Log_Space] FLOAT ,
	  [Status] VARCHAR(100)
	) 
 
INSERT	INTO @result
		EXEC ( 'DBCC sqlperf(LOGSPACE) WITH NO_INFOMSGS'
			)
 
-- only return for the DB in context, rounding it 
SELECT	ROUND([Log_Space], 2)
FROM	@result
WHERE	[Database_Name] = DB_NAME()

Instances to collect from

Select all

Databases to collect from

Collection frequency

300

Use collected or calculated values

Leave the Use a calculated rate of change between collections check box unchecked

Metric collection

Enabled

Alert definition

Alert name

Free log space decreased

Description

This alert is raised when the percentage of used space in the log transaction files (LDF) exceeds the specified thresholds.

Raise an alert when the metric value goes

Above the defined threshholds

Default threshold values

High:	90
Medium:	80
Low:	Disabled

Raise an alert when the threshold is passed for

1 collection

Alert is

Enabled

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Percentage of used log space

Metric definition

Name

Description

The T-SQL query that will collect data

Instances to collect from

Databases to collect from

Collection frequency

Use collected or calculated values

Metric collection

Alert definition

Alert name

Description

Raise an alert when the metric value goes

Default threshold values

Raise an alert when the threshold is passed for

Alert is

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