DB파일사이즈

2010. 6. 4. 01:15

DB파일사이즈

2010. 6. 4. 01:15 in Common Admin

Collecting database usage information for free space and trending

I find it important in my environment to monitor the following database/database file level metrics:

Server/Instance Name
Database Name
Database File Names (both logical and full physical path)
File Size (In Megabytes)
Database Status
Recovery Mode
Free Space (In Megabytes and Percent)

To collect this information I need to tap into the either the master.dbo.sysfiles system table in SQL 2000 or master.sys.sysfiles compatibility view in SQL 2005. I also need to make use of a few T-SQL functions at the DBA's disposal. First, let me present the query. Afterwards I'll explain the finer points.

DECLARE @DBInfo TABLE ( ServerName VARCHAR(100), DatabaseName VARCHAR(100), FileSizeMB INT, LogicalFileName sysname, PhysicalFileName NVARCHAR(520), Status sysname, Updateability sysname, RecoveryMode sysname, FreeSpaceMB INT, FreeSpacePct VARCHAR(7), FreeSpacePages INT, PollDate datetime) DECLARE @command VARCHAR(5000) SELECT @command = 'Use [' + '?' + '] SELECT @@servername as ServerName, ' + '''' + '?' + '''' + ' AS DatabaseName, CAST(sysfiles.size/128.0 AS int) AS FileSize, sysfiles.name AS LogicalFileName, sysfiles.filename AS PhysicalFileName, CONVERT(sysname,DatabasePropertyEx(''?'',''Status'')) AS Status, CONVERT(sysname,DatabasePropertyEx(''?'',''Updateability'')) AS Updateability, CONVERT(sysname,DatabasePropertyEx(''?'',''Recovery'')) AS RecoveryMode, CAST(sysfiles.size/128.0 - CAST(FILEPROPERTY(sysfiles.name, ' + '''' + 'SpaceUsed' + '''' + ' ) AS int)/128.0 AS int) AS FreeSpaceMB, CAST(100 * (CAST (((sysfiles.size/128.0 -CAST(FILEPROPERTY(sysfiles.name, ' + '''' + 'SpaceUsed' + '''' + ' ) AS int)/128.0)/(sysfiles.size/128.0)) AS decimal(4,2))) AS varchar(8)) + ' + '''' + '%' + '''' + ' AS FreeSpacePct, GETDATE() as PollDate FROM dbo.sysfiles' INSERT INTO @DBInfo (ServerName, DatabaseName, FileSizeMB, LogicalFileName, PhysicalFileName, Status, Updateability, RecoveryMode, FreeSpaceMB, FreeSpacePct, PollDate) EXEC sp_MSForEachDB @command SELECT ServerName, DatabaseName, FileSizeMB, LogicalFileName, PhysicalFileName, Status, Updateability, RecoveryMode, FreeSpaceMB, FreeSpacePct, PollDate FROM @DBInfo ORDER BY ServerName, DatabaseName

CAST(sysfiles.size/128.0 - CAST(FILEPROPERTY(sysfiles.name, ' + '''' + 'SpaceUsed' + '''' + ' ) AS int)/128.0 AS int) AS FreeSpaceMB

The FreeSpaceMB calculation is simple once you understand what I explained above for the calculations associated with FileSize. To determine free space we need to know how much of the total file space is being consumed. This information is exposed via the FILEPROPERTY() function. FILEPROPERTY() expects the following parameters: file name, and property.

Expect a future tip on the various uses for FILEPROPERTY(), but for now we focus on the SpaceUsed property. This value is also stored in 8Kb pages, so the factor of 1024/8 (or 128) remains constant. Using the same basic rules we discussed above this is what the formula would look like this: Available Space in Mb = (File Size in Mb) - (Space Used in Mb). The formula in the query casts all variables as integer data types and converts the available values from pages to Mb.

I know that one of the major foundations of database normalization is not storing calculated values in a database. However, I like to be able to trend my metadata over time and with the complexity of the formulas I prefer to do all my thinking up-front. That being said, I don't just store the size information in the table and run calculations in my queries after the fact - I do my calculations directly in the query that populates the repository.