Monitoring for Time Drift in your enterprise

#=================================================================================
#  Time Skew Monitoring Script
#  Kevin Holman
#  Version 1.0
#=================================================================================
param([string]$RefServer,[int]$Threshold)


#=================================================================================
# Constants section - modify stuff here:

# Assign script name variable for use in event logging
$ScriptName = "Demo.TimeDrift.PA.ps1"
# Set samples to the number of w32time samples you wish to include 
[int]$Samples = '1'
# For testing - assign values instead of paramtersto the script
#[string]$RefServer = 'dc1.opsmgr.net'
#[int]$Threshold = '10'
#=================================================================================

# Gather script start time
$StartTime = Get-Date

# Gather who the script is running as
$WhoAmI = whoami

# Load MomScript API and PropertyBag function 
$momapi = new-object -comObject 'MOM.ScriptAPI'
$bag = $momapi.CreatePropertyBag()

#Log script event that we are starting task
$momapi.LogScriptEvent($ScriptName,9250,0, "Starting script")


#Start MAIN body of script:

#Getting the required data
$cmd = w32tm /stripchart /computer:$RefServer /dataonly /samples:$Samples

IF ($cmd -match 'error')
{
  #Log error and quit
  $momapi.LogScriptEvent($ScriptName,9250,2, "Getting TimeDrift from Reference Server returned an error .  Reference server is ($RefServer).  Output of command is ($cmd)")
  exit
}
ELSE
{
  #Assume we got good results from cmd
  $Skew = $cmd[-1..($Samples * -1)] | ConvertFrom-Csv -Header "Time","Skew" | Select -ExpandProperty Skew
  $Result = $Skew | % { $_ -replace "s","" }   | Measure-Object -Average | select -ExpandProperty Average
}

#The problem is that you can have time skew in two directions: positive or negative. You can do two
#things: create an IF statement that does check both or just create a positive number.
IF ($Result -lt 0) { $Result = $Result * -1 }

$TimeDriftSeconds = [math]::Round($Result,2)

#Determine if the average time skew is higher than your threshold and report this back to SCOM.
IF ($TimeDriftSeconds -gt $Threshold)
{
  $bag.AddValue("TimeSkew","True")
  $momapi.LogScriptEvent($ScriptName,9250,2, "Time Drift was detected.  Reference server is ($RefServer).  Threshold is ($Threshold) seconds.  Value is ($TimeDriftSeconds) seconds")
}
ELSE
{
  $bag.AddValue("TimeSkew","False")
  #Log good event for testing
  #$momapi.LogScriptEvent($ScriptName,9250,0, "Time Drift was OK.  Reference server is ($RefServer).  Threshold is ($Threshold) seconds.  Value is ($TimeDriftSeconds) seconds") 
}

#Add stuff into the propertybag
$bag.AddValue("RefServer",$RefServer)
$bag.AddValue("Threshold",$Threshold)
$bag.AddValue("TimeDriftSeconds",$TimeDriftSeconds)

#Log an event for script ending and total execution time.
$EndTime = Get-Date
$ScriptTime = ($EndTime - $StartTime).TotalSeconds
$ScriptTime = [math]::Round($ScriptTime,2)
$momapi.LogScriptEvent($ScriptName,9250,0,"`n Script has completed. `n Reference server is ($RefServer). `n Threshold is ($Threshold) seconds. `n Value is ($TimeDriftSeconds) seconds. `n Runtime was ($ScriptTime) seconds.")

#Output the propertybag  
$bag