3. SQL Server数据库状态监控

数据库用来存放数据，那么肯定需要存储空间，所以对磁盘空间的监视自然就很有必要了。

一. 磁盘可用空间

1. 操作系统命令或脚本、接口或工具

(1) DOS命令: fsutil volume diskfree

C:/windows/system32>fsutil volume diskfree C:

Total # of free bytes : 9789493248

Total # of bytes : 64424505344

Total # of avail free bytes : 9789493248

这里用到了fsutil，一个文件系统管理工具(file system utility)，应该还有其他一些命令或者脚本也是可以的。

(2) WMI/WMIC: wmic logicaldisk

WMI是个Windows系统的管理接口，在WMIC出现之前，如果要利用WMI管理系统，必须使用一些专门的WMI应用，例如SMS，或者使用WMI的脚本编程API，或者使用象CIM Studio之类的工具。如果不熟悉C++之类的编程语言或VBScript之类的脚本语言，或者不掌握WMI名称空间的基本知识，要用WMI管理系统是很困难的。WMIC改变了这种情况，它为WMI名称空间提供了一个强大的、友好的命令行接口。

C:/windows/system32>wmic logicaldisk get caption,freespace,size

Caption FreeSpace Size

C: 9789071360 64424505344

D: 189013438464 255331397632

这里通过wmic的get命令获取了logicaldisk 的几个参数列。

(3) 性能监视器

LogicalDisk: %Free Space

LogicalDisk: Free Megabytes

总大小 = LogicalDisk: Free Megabytes/ LogicalDisk: %Free Space

性能监视器虽然用于现场诊断还是挺方便的，但实现自动化监控，并不太好用。

2. SQL 语句

(1) 扩展存储过程xp_cmdshell (还是在调用操作系统命令)

DECLARE @Drive TINYINT,      @SQL VARCHAR(100)DECLARE @Drives TABLE(Drive CHAR(1),Info VARCHAR(80))SET @Drive = 97WHILE @Drive <= 122BEGIN    SET @SQL = 'EXEC XP_CMDSHELL ''fsutil volume diskfree ' + CHAR(@Drive) + ':'''    INSERT @Drives    (    Info    )    EXEC(@SQL)    UPDATE @Drives       SET Drive = CHAR(@Drive)     WHERE Drive IS NULL    SET @Drive = @Drive + 1ENDSELECT Drive,SUM(CASE WHEN Info LIKE 'Total # of bytes%' THEN CAST(REPLACE(SUBSTRING(Info, 32, 48), CHAR(13), '') AS BIGINT) ELSE CAST(0 AS BIGINT) END)/1024.0/1024/1024 AS TotalMBytes,SUM(CASE WHEN Info LIKE 'Total # of free bytes%' THEN CAST(REPLACE(SUBSTRING(Info, 32, 48), CHAR(13), '') AS BIGINT) ELSE CAST(0 AS BIGINT) END)/1024.0/1024/1024 AS FreeMBytes,SUM(CASE WHEN Info LIKE 'Total # of avail free bytes%' THEN CAST(REPLACE(SUBSTRING(Info, 32, 48), CHAR(13), '') AS BIGINT) ELSE CAST(0 AS BIGINT) END)/1024.0/1024/1024 AS AvailFreeMBytesFROM(SELECT Drive,       Info  FROM @Drives WHERE Info LIKE 'Total # of %') AS dGROUP BY DriveORDER BY Drive

xp_cmdshell可以执行操作系统命令行，这段脚本用fsutil volume diskfree命令对26个字母的盘符遍历了一遍，不是很好，改用wmic会方便些，如下：

EXEC xp_cmdshell 'wmic logicaldisk get caption,freespace,size';

(2) 扩展存储过程xp_fixeddrives

--exec xp_fixeddrivesIF object_id('tempdb..#drivefreespace') IS NOT NULL    DROP TABLE #drivefreespaceCREATE TABLE #drivefreespace(Drive CHAR(1), FreeMb bigint)INSERT #drivefreespace EXEC ('exec xp_fixeddrives')SELECT * FROM #drivefreespace

总算不依赖操作系统命令了，不过，这个存储过程只能返回磁盘可用空间，没有磁盘总空间。

(3) DMV/DMF: sys.dm_os_volume_stats

SELECT DISTINCT       @@SERVERNAME as [server]      ,volume_mount_point as drive      ,cast(available_bytes/ 1024.0 / 1024.0 / 1024.0 AS INT) as free_gb      ,cast(total_bytes / 1024.0 / 1024.0 / 1024.0 AS INT) as total_gbFROM sys.master_files AS fCROSS APPLY sys.dm_os_volume_stats(f.database_id, f.file_id)ORDER BY @@SERVERNAME, volume_mount_point

从SQL Server 2008 R2 SP1开始，有了这个很好用的DMF: sys.dm_os_volume_stats，弥补了之前xp_fixeddrives没有磁盘总空间的不足。

不过，看它的参数就可以知道，没被任何数据库使用的磁盘，是查看不了的，所以xp_fixeddrives还有存在的必要。

二. 数据库可用空间

1. 文件可用空间查看

(1) 文件已用空间，当前大小(已分配空间)，最大值，如下：

select @@SERVERNAME as server_name      ,DB_NAME() as database_name      ,case when data_space_id = 0 then 'LOG'            else FILEGROUP_NAME(data_space_id)             end as file_group      ,name as logical_name      ,physical_name      ,type_desc      ,FILEPROPERTY(name,'SpaceUsed')/128.0 as used_size_Mb      ,size/128.0 as allocated_size_mb       ,case when max_size = -1 then max_size             else max_size/128.0             end as max_size_Mb      ,growth      ,is_percent_growth from sys.database_fileswhere state_desc = 'ONLINE'

(2) 再算上磁盘的空闲空间，改动如下：

select @@SERVERNAME as server_name      ,DB_NAME() as database_name      ,case when data_space_id = 0 then 'LOG'            else FILEGROUP_NAME(data_space_id)             end as file_group      ,name as logical_name      ,physical_name      ,type_desc      ,FILEPROPERTY(name,'SpaceUsed')/128.0 as used_size_mb      ,size/128.0 as allocated_size_mb      ,case when max_size = -1 then max_size                 else max_size/128.0                 end as max_size_mb      ,vs.available_bytes/1024.0/1024 as disk_free_mb      ,growth      ,CAST(is_percent_growth as int) as is_percent_growthfrom sys.database_files dfcross apply sys.dm_os_volume_stats(DB_ID(),df.file_id) vswhere state_desc = 'ONLINE'

如果是SQL Server 2008 SP1以前的版本，可用xp_fixeddrives生成磁盘空闲空间表，再进行关联。

(3) 结合文件是否自增长，文件最大值，磁盘空间，算出文件可用空间比率，改动如下：

select @@SERVERNAME as server_name      ,DB_NAME() as database_name      ,case when data_space_id = 0 then 'LOG'            else FILEGROUP_NAME(data_space_id)             end as file_group      ,name as logical_name      ,physical_name      ,type_desc      ,FILEPROPERTY(name,'SpaceUsed')/128.0 as used_size_mb      ,size/128.0 as allocated_size_mb      ,case when max_size = -1 then max_size                 else max_size/128.0                 end as max_size_mb      ,vs.available_bytes/1024.0/1024 as disk_free_mb      ,case when growth = 0 then  (size - FILEPROPERTY(name,'SpaceUsed'))*1.0/size            when growth > 0 and max_size = -1 then ((size/128.0 + vs.available_bytes/1024.0/1024) - FILEPROPERTY(name,'SpaceUsed')/128.0)/(size/128.0 + vs.available_bytes/1024.0/1024)            when growth