Powershell – Detect corrupted WMI

powershellwmi

When WMI is corrupted it will fail in the strangest ways, certain queries (most of them) will work, some will throw exceptions, others will time out and a few will simply return no (or partial/erroneous) results.

As I have a complicated important WMI system monitoring job I would like to be able to spot a corrupted WMI repository before I run the script. Determining it from the script behaviour is hard (due to the many ways WMI might fail) and often one can spend considerable time figuring out if its a system or WMI error.

I am essentially looking for a method tI can execute in the beginning of from my PowerShell script to determine beforehand if WMI is corrupted.

Best Answer

There is a script given away by Microsoft's Product Support Services team that's specifically designed to spot and diagnose corrupted WMI databases, the WMI Diagnostics Utility.

More info on how to use this at Troubleshooting WMI With WMIDiag.

Unfortunately I'm not too sure how useful this is going to be for you if you want to run this at the start of running a job, it's more the sort of thing that people tend to set to automatically run across their estate on a regular basis to report back on machines that need looking at.

Related Solutions

Powershell recursive WMI query

I think this will do what you are looking for in one line. the CIMV2 namespace is there by default but if you wanted to select a different one, you can use gwmi -namesapce.

The "trick" is nesting a where-object in side the foreach-object

gwmi -list | % {$_.Properties | ? {$_.Name.Contains('Memory')}} | select Origin,Name

Windows – Using Win32_FileSpecification WMI instances

there is no direct way to calculate an MD5 in PowerShell

That's not entirely true. Remember that PowerShell has access to the entire .NET stack, and it's certainly possible to compute an MD5 hash in .NET.

If your goal is to get an MD5 hash, then you can avoid WMI all together and use something like this:

$crypto = [System.Security.Cryptography.MD5]::Create()
$data = [System.IO.File]::ReadAllBytes("\\path\to\file")
$md5 = [System.Convert]::ToBase64String($crypto.ComputeHash($data))

Where md5 is a base64 encoded value of the MD5 hash.

Or if you need a hex representation instead of base64 of the hash:

$md5 = [System.BitConverter]::ToString($crypto.ComputeHash($data)).Replace("-", "")

You can of course wrap that up in a nice little PowerShell function:

Function MD5Hash
{
    param ($file)
    $crypto = [System.Security.Cryptography.MD5]::Create()
    $data = [System.IO.File]::ReadAllBytes($file)
    [System.BitConverter]::ToString($crypto.ComputeHash($data)).Replace("-", "")
}

And invoke like so:

MD5Hash "\\path\to\file"

Best Answer

Related Solutions

Powershell recursive WMI query

Windows – Using Win32_FileSpecification WMI instances

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