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 = 97
WHILE @Drive <= 122
BEGIN
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 + 1
END
SELECT 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 AvailFreeMBytes FROM(
SELECT Drive,
Info
FROM @Drives
WHERE Info LIKE 'Total # of %'
) AS d
GROUP BY Drive
ORDER 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_fixeddrives
IF object_id('tempdb..#drivefreespace') IS NOT NULL
DROP TABLE #drivefreespace
CREATE TABLE #drivefreespace(Drive CHAR(1), FreeMb bigint)
INSERT #drivefreespace EXEC ('exec xp_fixeddrives')
SELECT * FROM #drivefreespace
HSCSB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。
电力线适配器
(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_gb
FROM sys.master_files AS f
CROSS 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')/128.0as used_size_Mb
,size/128.0as 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_files
where 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')/128.0as used_size_mb
,size/128.0as allocated_size_mb
,case when max_size = -1 then max_size
else max_size/128.0
end as max_size_mb
,vs.available_bytes/1024.0/1024as disk_free_mb
,growth
,CAST(is_percent_growth as int) as is_percent_growth
from sys.database_files df
cross apply sys.dm_os_volume_stats(DB_ID(),df.file_id) vs
where 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)
全息打印end as file_group
,name as logical_name
,physical_name
,type_desc
,
FILEPROPERTY(name,'SpaceUsed')/128.0as used_size_mb
,size/128.0as allocated_size_mb
,case when max_size = -1 then max_size
else max_size/128.0
end as max_size_mb
,vs.available_bytes/1024.0/1024as 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 > 0 and max_size <> -1 and (max_size/128.0 - vs.available_bytes/1024.0/1024) >= 0 then ((size/128.0 + vs.available_bytes/1024.0/1024) - FILEPROPERTY(name,'SpaceUsed')/128.0)/(size/128.0 + vs.available_bytes/ when growth >
0 and max_size <> -1 and (max_size/128.0 - vs.available_bytes/1024.0/1024) < 0 then (max_size - FILEPROPERTY(name,'SpaceUsed'))*1.0/max_size
else null
end as free_space_percent
,growth
,CAST(is_percent_growth as int) as is_percent_growth
from sys.database_files df
cross apply sys.dm_os_volume_stats(DB_ID(),df.file_id) vs
where state_desc = 'ONLINE'
(4) 如果有多个数据库，注意fileproperty()和filegroup_name()函数，都只在当前数据库下⽣效，改动如下：
if object_id('tempdb..#tmp_filesize') is not null
drop table #tmp_filesize
GO
create table #tmp_filesize
人工鱼礁(
server_name varchar(256),
database_name varchar(256),
file_group varchar(256),
logical_name varchar(256),
physical_name varchar(1024),
type_desc varchar(128),
used_size_mb float,
allocated_size_mb float,
max_size_mb float,
disk_free_mb float,
free_space_percent float,
growth int,
is_percent_growth int
)
GO
exec sp_msforeachdb 'use [?]
insert into #tmp_filesize
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'')/128.0as used_size_mb
,size/128.0as allocated_size_mb催化剂评价
,case when max_size = -1 then max_size
else max_size/128.0
end as max_size_mb
,vs.available_bytes/1024.0/1024as 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 > 0 and max_size <> -1 and (max_size/128.0 - vs.available_bytes/1024.0/1024) >= 0 then ((size/128.0 + vs.available_bytes/1024.0/1024) - FILEPROPERTY(name,''SpaceUsed'')/128.0)/(size/128.0 + vs.available_bytes/ when growth > 0 and max_size <> -1 and (max_size/128.0 - vs.available_bytes/1024.0/1024) < 0 then (max_size - FILEPROPERTY(name,''SpaceUsed''))*1.0/max_size
else null
end as free_space_percent
,growth
,CAST(is_percent_growth as int) as is_percent_growth
from sys.database_files df
cross apply sys.dm_os_volume_stats(DB_ID(),df.file_id) vs
where state_desc = ''ONLINE'''
select * from #tmp_filesize
2.1 告警的格式
数据库可⽤空间告警，通常不告警某个⽂件，也不告警整个数据库，⽽是某个确切的⽂件组/表空间，⽇志⽂件是没有⽂件组的，所有可以把⽇志⽂件合并为LOG这个组。
(1) Oracle可以给表空间设置最⼤尺⼨，表空间⾥的每个⽂件逐个使⽤，直到最后⼀个⽂件也没空间时，就会提⽰空间不⾜；
(2) SQL Server ⽆法对⽂件组设置最⼤尺⼨，只可以给⽂件组⾥每个⽂件指定最⼤尺⼨，所以要先统
计：是否当前⽂件组下所有的⽂件都已经满了？
将同⼀个⽂件组/LOG下的所有⽂件都检查⼀下，如果所有⽂件都满了(以20%为例)，那么就满⾜告警条件了，如下：
--#tmp_filesize 在上⾯的脚本⾥⽣成了
select server_name,
database_name,
file_group,
MAX(free_space_percent) as max_free_space_percent
from #tmp_filesize
group by server_name,database_name,file_group
having MAX(free_space_percent) <= 0.2 --20%
邮件告警的格式⼤致为：
邮件标题：主机名\实例名\数据库名\⽂件组名，@@servername已经包含了SQL Server实例名；
邮件内容：⽂件组 ”file group name” 空间不⾜，已低于20%。
2.2 告警后如何处理？
(1) 告警中的⽂件组⾥的⽂件，所在的磁盘还有空间吗？
exec xp_fixeddrives
如果当前磁盘没空间，可以给当前⽂件组在其他磁盘上添加新的⽂件，并关闭⽼的⽂件⾃增长或限制最⼤值；
如果所有磁盘都没空间，可以考虑删除磁盘上的其他⽂件，或者收缩数据库⽂件(数据/⽇志)，或者磁盘扩展空间(加磁盘)。
(2) 如果磁盘有空间，⽂件是否关闭了⾃动增长？
可能是在创建⽂件时，给了⽂件⽐较⼤的size，如500G，并关闭了⽂件⾃动增长；
ALTER DATABASE test
ADD FILE
(
NAME = test_02,
FILENAME = 'D:\Program Files (x86)\Microsoft SQL Server\MSSQL10_50.MSSQLSERVER\MSSQL\DATA\test_02.ndf',
SIZE = 500 GB,支架搬运车
FILEGROWTH = 0
)
TO FILEGROUP [PRIMARY];
GO
(3) 如果磁盘有空间，⾃动增长也开了，是不是限制了⽂件最⼤值？
限制最⼤值和关闭⾃增长，应该都是不想单个⽂件变得太⼤，个⼈觉得⼀个⽂件控制在500G以内⽐较合理，这两种情况，都建议扩展⼀个新⽂件。
⼩结
如果没有监控⼯具，那么可选择系统视图，扩展存储过程，结合数据库邮件的⽅式，作⾃动检查，并告警⽂件组/⽇志空闲空间不⾜。⼤致步骤如下：
(1) 部署数据库邮件；
(2) 部署作业：定时检查⽂件组/⽇志空闲空间，发邮件告警。
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