17 October 2012

Percentage of database free space

by Muhammad Al Pasha

22,101 0 Storage

This metric measures the percentage of database free space - both reserved and unused - to help you manage space requirements more efficiently. For example, you might find this data helps you to correctly estimate file size, so you don't suffer from problems with automatic file growth.

Install metric...

Metrics install automatically if you have Redgate Monitor installed.

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 database free space – both reserved and unused – to help you manage space requirements more efficiently. For example, you might find this data helps you to correctly estimate file size, so you don’t suffer from problems associated with automatic file growth.

Metric definition

Name

Percentage of database free space

Description

The T-SQL query that will collect data


		
			
			
Transact-SQL
			
			SELECT (AU.unallocated + AU.unused) * 100 / (AU.reserved + AU.unallocated) AS free_space_pct
  FROM (SELECT AU.reserved,
               AU.reserved - AU.used AS unused,
               CASE WHEN SF.db_size >= AU.reserved THEN (SF.db_size - AU.reserved) ELSE 0 END AS unallocated
          FROM (SELECT SUM(CAST(CASE WHEN SF.status & 64 = 0 THEN SF.size ELSE 0 END AS DECIMAL(38, 2))) AS db_size
                  FROM dbo.sysfiles AS SF) AS SF
               CROSS JOIN
               (SELECT SUM(CAST(A.total_pages AS DECIMAL(38, 2))) AS reserved,
                       SUM(CAST(A.used_pages AS DECIMAL(38, 2))) AS used
                  FROM sys.partitions AS P
                       INNER JOIN
                       sys.allocation_units AS A
                       on A.container_id = P.partition_id) AS AU) AS AU;
			
				
					
				
					1
2
3
4
5
6
7
8
9
10
11
12
13
				
						SELECT (AU.unallocated + AU.unused) * 100 / (AU.reserved + AU.unallocated) AS free_space_pct
  FROM (SELECT AU.reserved,
               AU.reserved - AU.used AS unused,
               CASE WHEN SF.db_size >= AU.reserved THEN (SF.db_size - AU.reserved) ELSE 0 END AS unallocated
          FROM (SELECT SUM(CAST(CASE WHEN SF.status & 64 = 0 THEN SF.size ELSE 0 END AS DECIMAL(38, 2))) AS db_size
                  FROM dbo.sysfiles AS SF) AS SF
               CROSS JOIN
               (SELECT SUM(CAST(A.total_pages AS DECIMAL(38, 2))) AS reserved,
                       SUM(CAST(A.used_pages AS DECIMAL(38, 2))) AS used
                  FROM sys.partitions AS P
                       INNER JOIN
                       sys.allocation_units AS A
                       on A.container_id = P.partition_id) AS AU) AS AU;

Instances to collect from

Select all

Databases to collect from

Collection frequency

1800

Note: If this frequency is too low or too high for your needs, choose an alternative option.

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

Low database free space

Description

The amount of free space for this database (including reserved and unused space) is low.

Raise an alert when the metric value goes

Below the defined threshholds

Default threshold values

High:	10
Medium:	20
Low:	30

Note: These thresholds are intended as guideline values. If they seem too high or too low for your environment, replace them with values more suited to your server performance.

Raise an alert when the threshold is passed for

3 collections

Alert is

Enabled

22,101 Rate

Click to rate this post!

[Total: 12 Average: 4.2]

Percentage of database free 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

What are custom metrics?

What is Redgate Monitor?

Featured custom metrics

Total database file size

Number of active backups and restores

Full backup to odd path

Find metrics