How to get powershell to read a SQL Server error log - sql-server

Question

I need your help with PowerShell today. I have a SQL Server instance (on a server named VMDEV-APP11) configured as a Central Management Server (CMS) in which I have registered all my Dev/Test/Prod SQL instances and I want to use PowerShell to read the SQL Server error logs from all my servers. I have a query which retrieves all my SQL Server instances but when I pipe the output of this into a call to ReadErrorLog, I get an error.
This is the code that retrieves my list of the SQL Server instances which are registered on my CMS (note that I exclude my SQL Server 2000 instances):
Set-Location D:\MSSQL11.MSSQLSERVER\CMS
# Define functions to query SQL Server and write data to a SQL table
. ./invoke-sqlcmd2.ps1
. ./write-datatable.ps1
Invoke-sqlcmd2 -ServerInstance "VMDEV-APP11" -Database dba -Query "select s.server_name from msdb.dbo.sysmanagement_shared_registered_servers s, msdb.dbo.sysmanagement_shared_server_groups g where s.server_group_id = g.server_group_id and g.name not like '2000%'"
server_name
-----------
INF-SRV14
VMDEV-APP15
NEX-SRV48
...
And this is what I thought would work and the error I actually get:
Invoke-sqlcmd2 -ServerInstance "VMDEV-APP11" -Database dba -Query "select s.server_name from msdb.dbo.sysmanagement_shared_registered_servers s, msdb.dbo.sysmanagement_shared_server_groups g where s.server_group_id = g.server_group_id and g.name not like '2000%'" | foreach-object { $_.server_name.ReadErrorLog() }
Error:
Method invocation failed because [System.String] does not contain a method named 'ReadErrorLog'.
At D:\MSSQL11.MSSQLSERVER\CMS\db_errorlog.ps1:38 char:284
+ ... reach-object { $_.server_name.ReadErrorLog() }
+ ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+ CategoryInfo : InvalidOperation: (:) [], RuntimeException
+ FullyQualifiedErrorId : MethodNotFound
I suspect I need to convert the string returned by my query to another type of object (a server name perhaps?) in order to get the ReadErrorLog() call to work but I don't know how to do that.
Any suggestions?
Any help would be greatly appreciated.
Ken

Answer 1

You're trying to invoke the ReadErrorLog() method on a DataRow column value, which is a string.
What you need to do is something like this:
Import-Module sqlps -DisableNameChecking
Invoke-sqlcmd2 -ServerInstance "VMDEV-APP11" -Database dba -Query "select s.server_name from msdb.dbo.sysmanagement_shared_registered_servers s, msdb.dbo.sysmanagement_shared_server_groups g where s.server_group_id = g.server_group_id and g.name not like '2000%'" | `
foreach-object {
$server = $_.server_name
$logs = (get-item SQLSERVER:\sql\$server\default).ReadErrorLog()
# $logs is a DataTable so you can iterate the rows however you wish
}
This assuming all your servers are default instances, otherwise you may need to fiddle around a bit more to target specific instances.

Answer 2

The code I'm running on my SQL Central Management server is:
$logs = 0..6 | % { (get-item SQLSERVER:\sql\<servername>\default).ReadErrorLog($_) }
Originally, I got this to work by adding the service account that ran the PowerShell code to the local Administrators Windows group AND creating a SQL login with sysadmin privileges on the remote SQL server host. Not sursprisingly, my security officer had an issue with this. My initial attempts to reduce access resulted i the following error:
WARNING: Could not obtain SQL Server Service information. An attempt to connect
to WMI on 'NEX-SRV1' failed with the following error: SQL Server WMI provider
is not available on NEX-SRV1. --> Invalid namespace
After quite a bit of fooling around, I have what I think is the minimum security needed to read the SQL error logs. Perform the following grants on the remote server running the SQL Server database:
Local Windows Group
Add the service account to the "Distributed COM Users" group
WMIMgmt.msc
Add the service account to each of the following branches with all security options EXCEPT "Edit Security"
Root > cimv2
Root > cimv2 > ms_409
Root > Microsoft > SQLServer > ComputerManagement
SQL Server
Create a SQL login for the service account and add it to the "Security Admin" role.
After I had made these changes, I have the ability to monitor SQL Error logs from a central location without having to grant crazy levels of access to the service account.