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We are using 6 databases in total for an application, and we can only share 4TB of space among all 6 auto-grow databases (via SAN storage).

I'd like to write a query (report) for a single database indicating the "Currently allocated space" and "Available free space" attributes under the Tasks > Shrink > Database option in SQL Server Management Studio.

Then I'd like to convert those numbers to TB and total each database to get a rough estimate of how much space we have left. Can these fields be accessed via a T-SQL query? If so, what would the query look like?

Shrink Database Dialog

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up vote 19 down vote accepted

Here is the query Management Studio uses to populate those numbers:

(SELECT SUM(CAST(df.size as float)) FROM sys.database_files AS df 
   WHERE df.type in ( 0, 2, 4 ) ) AS [DbSize],
SUM(a.total_pages) AS [SpaceUsed],
(SELECT SUM(CAST(df.size as float)) FROM sys.database_files AS df 
   WHERE df.type in (1, 3)) AS [LogSize]
sys.partitions p join sys.allocation_units a 
  on p.partition_id = a.container_id 
left join sys.internal_tables it 
  on p.object_id = it.object_id

You need to perform math here just like Management Studio does in order to get the same numbers. Also, the left join to sys.internal_tables seems superfluous at best. So adjusting that query to match your ideal output:

(SELECT CONVERT(DECIMAL(18,2), SUM(CAST(df.size as float))*8/1024.0)
   FROM sys.database_files AS df 
   WHERE df.type in ( 0, 2, 4 ) ) AS [DbSize],
CONVERT(DECIMAL(18,2), SUM(a.total_pages)*8/1024.0) AS [SpaceUsed],
(SELECT CONVERT(DECIMAL(18,2), SUM(CAST(df.size as float))*8/1024.0)
   FROM sys.database_files AS df 
   WHERE df.type in (1, 3)) AS [LogSize]
FROM sys.partitions p join sys.allocation_units a 
  on p.partition_id = a.container_id;

With this update, assuming your database doesn't change in the meantime, it should yield:

753475.94    744030.07    2900.00

Doing some simple math, and isolating just the three numbers you want:

;WITH t(s) AS
  SELECT CONVERT(DECIMAL(18,2), SUM(size)*8/1024.0)
   FROM sys.database_files
   WHERE [type] % 2 = 0
d(s) AS
  SELECT CONVERT(DECIMAL(18,2), SUM(total_pages)*8/1024.0)
   FROM sys.partitions AS p
   INNER JOIN sys.allocation_units AS a 
   ON p.[partition_id] = a.container_id
  Allocated_Space = t.s, 
  Available_Space = t.s - d.s,
  [Available_%] = CONVERT(DECIMAL(5,2), (t.s - d.s)*100.0/t.s)
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Aaron's query is good, but as an alternative, I use this query from Glenn Berry's DMV Queries
(you would need to change the math for TBs):

-- Individual File Sizes and space available for current database
-- (Query 36) (File Sizes and Space)
SELECT AS [File Name] , f.physical_name AS [Physical Name], 
CAST((f.size/128.0) AS DECIMAL(15,2)) AS [Total Size in MB],
CAST(f.size/128.0 - CAST(FILEPROPERTY(, 'SpaceUsed') AS int)/128.0 AS DECIMAL(15,2)) 
AS [Available Space In MB], [file_id], AS [Filegroup Name]
FROM sys.database_files AS f WITH (NOLOCK) 
LEFT OUTER JOIN sys.data_spaces AS fg WITH (NOLOCK) 
ON f.data_space_id = fg.data_space_id OPTION (RECOMPILE);
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Here's some SQL that might work for you.

Create Table #dbInfo (dId smallint, dbName sysname, gId smallint NULL, segName varchar(256) NULL, 
       filName varchar(520) NULL, sizeMg decimal(10,2) null, 
       usedMg decimal(10,2) null, freeMg decimal(10,2) null, 
       pcntUsed decimal(10,2) null, pcntFree decimal(10,2) null)
Declare @sSql varchar(1000)
Set @sSql = 'Use [?];
Insert #dbInfo (dId, dbName, gid, segName, filName, sizeMg, usedMg)
Select db_id(), db_name(), groupid, rtrim(name), filename, Cast(size/128.0 As Decimal(10,2)), 
Cast(Fileproperty(name, ''SpaceUsed'')/128.0 As Decimal(10,2))
From dbo.sysfiles Order By groupId Desc;'
Exec sp_MSforeachdb @sSql
Update #dbInfo Set
freeMg = sizeMg - usedMg,
pcntUsed = (usedMg/sizeMg)*100,
pcntFree = ((sizeMg-usedMg)/sizeMg)*100

select * from #dbInfo compute sum(sizeMG),  sum(FreeMg) 
drop table #dbInfo

It's old SQL but still works. One of these days I'm going to rewrite it to use the sys.database_files like the answer from Aaron.

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Msg 156, Level 15, State 1, Line 17 Incorrect syntax near the keyword 'compute'. – Server System Specialist Jul 23 '14 at 0:04

After working on a similar question (Querying True Physical Database File Sizes), I think a query that display the different file sizes, separated, e.g. by log and database, and the size of the file on disk would be more helpful to most users.

This includes the system file size and how much space it's taking on disk, as well as the SQL file size, SQL space used, and by extension SQL free space as well. It includes the full path of the file being evaluated. A user would need to change the calculation for 'Size_On_Disk_Bytes' if the disk is formatted using an allocation size different from the default (4096 bytes).

SELECT fg.data_space_id AS FGID,
   (f.file_id) AS File_Id,
   -- As provided by OP, size on disk in bytes.
   REPLACE(CONVERT(VARCHAR,CONVERT(MONEY, CAST(f.size AS FLOAT) * 8.00 * 1024), 1), '.00','') AS Size_On_Disk_Bytes,
   ROUND((CAST(f.size AS FLOAT) * 8.00/1024)/1024,3) AS Actual_File_Size,
   ROUND(CAST((f.size) AS FLOAT)/128,2) AS Reserved_MB,
   ROUND(CAST((FILEPROPERTY(,'SpaceUsed')) AS FLOAT)/128,2) AS Used_MB,
   ROUND((CAST((f.size) AS FLOAT)/128)-(CAST((FILEPROPERTY(,'SpaceUsed'))AS FLOAT)/128),2) AS Free_MB,,
FROM sys.database_files f 
    LEFT JOIN sys.filegroups fg
    ON f.data_space_id = fg.data_space_id

In addition, this query will return information about the space on the volume drive that hosts the files. The user will need to have access to sys.master_files.

SELECT DISTINCT dovs.logical_volume_name AS LogicalName,
dovs.volume_mount_point AS Drive,
CONVERT(INT,dovs.available_bytes/1048576.0) AS FreeSpaceInMB
FROM sys.master_files mf
CROSS APPLY sys.dm_os_volume_stats(mf.database_id, mf.FILE_ID) dovs
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