早晨宁波那边的IT人员打电话告知数据库无法访问了。其实我在早晨也发现Ignite监控下的宁波的数据库服务器出现了异常，但是当时正在检查查看其它服务器发过来的各类邮件，还没等到我去确认具体情况，就收到了电话。我首先检查网络是否畅通，结果发现网络没有问题，然后远程登录到该服务器，查看了一下数据库的服务发现其运行正常，但是在本机使用MSSMS管理工具亦无法连接数据库，当下有两种方案：方案一：使用DAC登录数据库，检查具体情况，方案二:直接去查看错误日志，查看具体错误信息。于是为了快点找到原因。我选择了去查看错误日志（C:\Program Files\Microsoft SQL Server\MSSQL.2\MSSQL\LOG）。
日期 2014/3/4 8:51:52
日志 SQL Server (存档编号3 - 2014/3/4 8:55:00)
源 Logon
消息
SQL Server failed with error code 0xc0000000 to spawn a thread to process a new login or connection. Check the SQL Server error log and the Windows event logs for information about possible related problems. [CLIENT: xxx.xxx.xxx.xxx]
在网上搜索了一下发现： This problem occurs because the Windows operating system pages out the working set of the SQL Server process.Means sql server needed more memory for that but showing less for a process..
因为这台服务器是Windows Server 2003 Stanard 32bit ， 物理内存4G，内存一直比较吃紧，本来计划迁移到新服务器，但是由于各种原因一直没有实施。 于是我重启了SQL Server 服务后，发现问题解决了。继续查找错误日志记录中最早出现“Error: 17189, Severity: 16, State:1"的时间点，发现是在早晨2014/3/4 8:02:49, 在此之前出现了
”AppDomain 4（YourSQLDba.dbo[runtime].3) is marked for unload due to memroy pressure
SQL Server Agent有如下错误信息：
关于这个问题， http://www.nullskull.com/q/10143638/error--17189.aspx 这里做了详细的介绍。
- To resolve the known issues that cause the Windows operating system to page out the working set of the SQL Server process, apply the hotfixes that are described in the following Microsoft Knowledge Base articles.
Note Hotfixes are cumulative. A later version of a hotfix contains the earlier versions of that hotfix.- Microsoft has found an issue that may cause the 64-bit edition of the SQL Server working set to be trimmed. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
http://support.microsoft.com/kb/905865/ (http://support.microsoft.com/kb/905865/ ) The sizes of the working sets of all the processes in a console session may be trimmed when you use Terminal Services to log on to or log off from a computer that is running Windows Server 2003
- Computers that are running Windows Server 2003 can be too aggressive when they cache dirty buffers if there is an application performing buffered I/O, such as a file copy operation. This behavior can cause the working set in SQL Server to be trimmed. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
http://support.microsoft.com/kb/920739/ (http://support.microsoft.com/kb/920739/ ) You may experience a decrease in overall system performance when you are copying files that are larger than approximately 500 MB in Windows Server 2003 S or in Windows Server 2003 S
- The SQL Server working set may be trimmed when the system is using some advanced TCP features. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
http://support.microsoft.com/kb/942861/ (http://support.microsoft.com/kb/942861/ ) Error message when an application connects to SQL Server on a server that is running Windows Server 2003: "General Network error," "Communication link failure," or "A transport-level error"
- On a multiprocessor computer that is running Windows Server 2003, the System process may consume most of the available system memory. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
http://support.microsoft.com/kb/942486/ (http://support.microsoft.com/kb/942486/ ) The System process may consume most of the available system memory on a multiprocessor computer that is running Windows Server 2003
- Microsoft has found an issue that may cause the 64-bit edition of the SQL Server working set to be trimmed. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
- If a device driver uses the MmAllocateContiguousMemory function, and if it sets the value of the HighestAcceptableAddress parameter to less than 4 gigabytes (GB), the Windows operating system may page out the working set of the 64-bit SQL Server process. To resolve this problem, contact the vendor of the device driver for driver updates.
- If you still encounter these problems after you apply these hotfixes, apply a Windows hotfix that limits the number of trim operations per process. For more information, click the following article numbers to view the articles in the Microsoft Knowledge Base:
http://support.microsoft.com/kb/938486/ (http://support.microsoft.com/kb/938486/ ) A Windows Server 2003-based computer becomes unresponsive because of a memory manager trimming operation that is caused by an indeterminate module that requests lots of memory
http://support.microsoft.com/kb/956341/ (http://support.microsoft.com/kb/956341/ ) A Windows Server 2003-based computer becomes unresponsive because of a large memory allocation request
When a device driver tries to allocate memory, the Windows operating system may page out the working set of other applications. This Windows hotfix lets you use event tracing to find the device driver that causes problem.
- Applications may use the system cache too much, and may cause a large growth of the system cache. To respond to the growth of the system cache, the system pages out the working set of the SQL Server process or of other applications. If you experience this problem, you can use some memory management functions in the application. These functions control the system cache space that file I/O operations can use in the application. For example, you can use the SetSystemFileCacheSize function and the GetSystemFileCacheSize function to control the system cache space that file I/O operations can use.
You can use the Memory performance object to view the values of various counters in this object to determine whether the system cache working set uses too much memory. For example, you can view the Cache Bytes and System Cache Resident Bytes counters. For more information about this topic, visit the following Microsoft Web sites:http://blogs.msdn.com/ntdebugging/archive/2007/11/27/too-much-cache.aspx (http://blogs.msdn.com/ntdebugging/archive/2007/11/27/too-much-cache.aspx)
http://blogs.msdn.com/ntdebugging/archive/2009/02/06/microsoft-windows-dynamic-cache-service.aspx (http://blogs.msdn.com/ntdebugging/archive/2009/02/06/microsoft-windows-dynamic-cache-service.aspx)You can download and deploy the "Microsoft Windows Dynamic Cache Service" to control the memory that is consumed by the system cache.
- If SQL Server is running together with SAP R/3, you may experience a paging issue. For more information, click the following article number to view the article in the Microsoft Knowledge Base:
http://support.microsoft.com/kb/931308/ (http://support.microsoft.com/kb/931308/ ) You may experience increased paging to the hard disk when you run an SAP R/3 program on a Windows Server 2003-based computer
参考资料：
http://www.nullskull.com/q/10143638/error--17189.aspx
