Monday, February 24, 2014

Finding large time changes (windows)

When you are looking at time sync problems on newer Microsoft OS's (2008+), there are several places that may show useful information. Looking in the system log, you can find various events from the source: Time-Service, which tell you what server you are syncing with, if the servers are not available, if you domain controller is advertising time, and other various issues. In addition to that, another source: Kernel-General, may have some useful information. In Event ID #1 of this source, you will see occasional clock changes on the system. It gives both the old DateTime and the new one. This helps show you when large changes to the clock happen, so you can help historically see problematic servers. So, to collect and view this information in a more useful way, I came up with this example:

get-winevent -FilterHashtable @{logname="system"; providername="Microsoft-Windows-Kernel-General"; ID=1}|select -first 100 -Property TimeCreated,Properties,MachineName | foreach {
     $comp = $_.machinename
     $timeskew = new-timespan -start $[0].value -end $[1].value
     $timeskew = [int][math]::abs($timeskew.totalminutes)
     new-object PSObject -property @{
           EventDate = $_.TimeCreated
          TimeDiffMinutes = $timeskew
}|where {$_.TimeDiffMinutes -gt 2}

Here we use Get-WinEvent with a filterhash table to get the events we want. I'm just looking at a limited result here. In each event there are 2 properties which contain the two DateTime values. I'm putting that into a timespan to pull the difference in minutes, removing any negative value and printing out the machinename, Timeskew in minutes and when the change was done. You can add -computer to the initial Get-Winevent to run a list of machines.

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