环境描述
Windows 2012 R2，SharePoint 2013(没有sp1补丁)，sql server 2012
错误描述
搜索服务正常，但是爬网一直在Crawling Full，但是爬不到任何东西，而且不会停止，爬了一宿什么都没有爬到：
爬网不止，爬了一宿什么都没有爬到，错误如下：
去15/logs里面找日志；
Non-OAuth request. IsAuthenticated=True, UserIdentityName=0#.w|domain\user, ClaimsCount=125 b5b2d49c-feb7-e08b-ecf7-28204da68508
UserAgent not available, file operations may not be optimized. at Microsoft.SharePoint.SPFileStreamManager.CreateCobaltStreamContainer(SPFileStreamStore spfs, ILockBytes ilb, Boolean copyOnFirstWrite, Boolean disposeIlb) at Microsoft.SharePoint.SPFileStreamManager.SetInputLockBytes(SPFileInfo& fileInfo, SqlSession session, PrefetchResult prefetchResult) at Microsoft.SharePoint.CoordinatedStreamBuffer.SPCoordinatedStreamBufferFactory.CreateFromDocumentRowset(Guid databaseId, SqlSession session, SPFileStreamManager spfstm, Object[] metadataRow, SPRowset contentRowset, SPDocumentBindRequest& dbreq, SPDocumentBindResults& dbres) at Microsoft.SharePoint.SPSqlClient.GetDocumentContentRow(Int32 rowOrd, Object ospFileStmMgr, SPDocumentBindRequest& dbreq, SPDocumentBindResults& dbres...
The crawler could not communicate with the server. Check that the server is available and that the firewall access is configured correctly.
事件查看器报错；
WebHost failed to process a request.
Sender Information: System.ServiceModel.ServiceHostingEnvironment+HostingManager/63363381
Exception: System.ServiceModel.ServiceActivationException: The service '/90ac4adbb96a4e89892b2ad7ab02da51/MetadataWebService.svc' cannot be activated due to an exception during compilation. The exception message is: The farm is unavailable.. ---> System.InvalidOperationException: The farm is unavailable.
at Microsoft.SharePoint.Administration.Claims.SPSecurityTokenServiceManager.get_Local()
at Microsoft.SharePoint.IdentityModel.SPServiceIssuerNameRegistry..ctor()
at Microsoft.SharePoint.SPServiceHostOperations.Configure(ServiceHostBase serviceHost, SPServiceAuthenticationMode authenticationMode)
at Microsoft.SharePoint.Taxonomy.MetadataWebServiceHostFactory.CreateServiceHost(String constructorString, Uri[] baseAddresses)
at System.ServiceModel.ServiceHostingEnvironment.HostingManager.CreateService(String normalizedVirtualPath, EventTraceActivity eventTraceActivity)
at System.ServiceModel.ServiceHostingEnvironment.HostingManager.ActivateService(ServiceActivationInfo serviceActivationInfo, EventTraceActivity eventTraceActivity)
at System.ServiceModel.ServiceHostingEnvironment.HostingManager.EnsureServiceAvailable(String normalizedVirtualPath, EventTraceActivity eventTraceActivity)
--- End of inner exception stack trace ---
at System.ServiceModel.ServiceHostingEnvironment.HostingManager.EnsureServiceAvailable(String normalizedVirtualPath, EventTraceActivity eventTraceActivity)
at System.ServiceModel.ServiceHostingEnvironment.EnsureServiceAvailableFast(String relativeVirtualPath, EventTraceActivity eventTraceActivity)
Process Name: w3wp
Process ID: 6004
解决方法
事件查看器错误，参考下面link解决，但是没有解决爬网的问题：
经过一天的挣扎，终于决定删掉搜索服务，重建！经过重建，发现报错更严重了，搜索主机控制服务连不上了；然后，查看搜索主机控制服务，发现和搜索服务运行账号不是一个，更新成一个以后，搜索服务正常了，爬网也没有问题了！
其他参考
解决过程中，发现其他人遇到过类似问题，跟自己原因不同，备注下面给大家一个参考；