SQL Server误设置max server memory的处理方法

昨天网上一网友说，由于他同事误将“max server memory”设置为10M后，SQL Server数据库登录不了，当时我简单测试了一下，今天有空就顺手将整个过程整理一下，记录在此。

在SSMS的UI界面设置“max server memory”，即使你设置为10M大小，但是它会“悄悄”默认修改为128M，你用Profile跟踪或者设置后会发现，它偷偷“修改”了你的设置值（改为了128M），

EXEC sys.sp_configure N'max server memory (MB)', N'128'
GO
RECONFIGURE WITH OVERRIDE
GO
 
Configuration option 'max server memory (MB)' changed from 4096 to 128. Run the RECONFIGURE statement to install.

如果你没有注意这些细节，或者不信这个事情，那么也可以用脚本测试一下，如下所示，它提示你这个值（10M）不是一个有效值。

当你对“max server memory”做了错误设置后，那么基本上，任何查询或连接都会出现类似下面这样的错误：

An exception occurred while executing a Transact-SQL statement or batch. (Microsoft.SqlServer.ConnectionInfo)
 
------------------------------
There is insufficient system memory in resource pool 'internal' to run this query. (Microsoft SQL Server, Error: 701)
 
 
 
 
 
 
------------------------------
ADDITIONAL INFORMATION:
 
A connection was successfully established with the server, but then an error occurred during the pre-login handshake. (provider: TCP Provider, error: 0 - 远程主机强迫关闭了一个现有的连接。) (Microsoft SQL Server, Error: 10054)
 
For help, click: http://go.microsoft.com/fwlink?ProdName=Microsoft%20SQL%20Server&EvtSrc=MSSQLServer&EvtID=10054&LinkId=20476
 
------------------------------
远程主机强迫关闭了一个现有的连接。 

你检查数据库的错误日志，就会发现有很多额外信息，摘抄部分如下：

.........................................................
.........................................................
2019-12-24 10:15:32.84 spid53      There is insufficient system memory in resource pool 'internal' to run this query.
2019-12-24 10:15:52.88 spid53      Error: 18056, Severity: 20, State: 29. (Params:). The error is printed in terse mode because there was error during formatting. Tracing, ETW, notifications etc are skipped.
2019-12-24 10:15:55.89 Server      Error: 17300, Severity: 16, State: 1. (Params:). The error is printed in terse mode because there was error during formatting. Tracing, ETW, notifications etc are skipped.
2019-12-24 10:16:12.70 Server       Failed allocate pages: FAIL_PAGE_ALLOCATION 1
2019-12-24 10:16:12.70 Server  
 
Process/System Counts                         Value
---------------------------------------- ----------
Available Physical Memory                6614454272
Available Virtual Memory                 140726213148672
Available Paging File                    7776440320
Working Set                                95432704
Percent of Committed Memory in WS               100
Page Faults                                   57030
System physical memory high                       1
System physical memory low                        0
Process physical memory low                       1
Process virtual memory low                        0
2019-12-24 10:16:12.70 Server     
Memory Manager                                   KB
---------------------------------------- ----------
VM Reserved                                10652776
VM Committed                                  57972
Locked Pages Allocated                        86472
Large Pages Allocated                             0
Emergency Memory                               1024
Emergency Memory In Use                          16
Target Committed                             131072
Current Committed                            144448
Pages Allocated                               84176
Pages Reserved                                    0
Pages Free                                        0
Pages In Use                                 144432
Page Alloc Potential                         -19912
NUMA Growth Phase                                 2
Last OOM Factor                                   1
Last OS Error                                     0
2019-12-24 10:16:12.70 Server     
Memory node Id = 0                               KB
---------------------------------------- ----------
VM Reserved                                10652712
VM Committed                                  57952
Locked Pages Allocated                        86472
Pages Allocated                               84176
Pages Free                                        0
Target Committed                             131048
Current Committed                            144424
Foreign Committed                                 0
Away Committed                                    0
Taken Away Committed                              0
2019-12-24 10:16:12.70 Server     
Memory node Id = 64                              KB
---------------------------------------- ----------
VM Reserved                                       0
VM Committed                                     20
Locked Pages Allocated                            0
2019-12-24 10:16:12.70 Server     
MEMORYCLERK_SQLGENERAL (node 0)                  KB
---------------------------------------- ----------
.........................................................
......................................................... 

要解决这个问题，你需要关闭数据库服务， 然后以单用户模式+最小配置启动数据库实例，然后去修改max server memory参数。 关闭数据库过程中如果遇到一些问题，可以通过重启服务器解决问题（这个要根据具体实际情况决定，有时候不会遇到问题，有时候会遇到一些问题，例如net stop mssqlserver命令卡住，出现service_state[MSSQLSERVER]): Stop pending）

注意：如果以单用户模式启动，然后以sqlcmd去连接数据库，就会出现下面错误，所以必须以单用户模式+最小配置启动数据库实例

EXEC sys.sp_configure 'max server memory (MB)',4096; #根据实际情况设置内存大小。
 
RECONFIGURE
 
GO

然后重启SQL Server实例，问题就解决了。 当然你也可以还原master库的备份到其它测试数据库，然后用还原后master数据库的相关文件替换当前数据库master的相关文件来解决问题。但是那样会相对麻烦，没有这种方法简便、有效！

C:\Windows\system32>net stop mssqlserver

The SQL Server (MSSQLSERVER) service is stopping.

The SQL Server (MSSQLSERVER) service was stopped successfully.

C:\Windows\system32>net start mssqlserver

The SQL Server (MSSQLSERVER) service is starting.

The SQL Server (MSSQLSERVER) service was started successfully.

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