ULS 日志为空

解决方案：

1.保存为ChangeAccounts_SPTraceV4.ps1，运行

# Get the tracing service.
$farm = Get-SPFarm
$tracingService = $farm.Services | where {$_.Name -eq "SPTraceV4"}
# Get the "svc_sp_services" managed account.
$managedAccount = Get-SPManagedAccount "****\defaultService"
# Set the tracing service to run under the managed account.
$tracingService.ProcessIdentity.CurrentIdentityType = "SpecificUser"
$tracingService.ProcessIdentity.ManagedAccount = $managedAccount
$tracingService.ProcessIdentity.Update()
# This actually changes the "Run As" account of the Windows service.
$tracingService.ProcessIdentity.Deploy()

2.将"****\defaultService“加入到本地组 Performance Log Users 中

3.重启SPTraceV4服务

参考：http://blog.octavie.nl/index.php/2010/11/12/using-a-domain-account-for-sptracev4-service/