30 Aralık 2011 Cuma

Network utilization scripts in BaseOS MP version 6.0.6958.0 may cause high CPU utilization

One of the changes in this newer version of the MP is the addition of a new datasource module, which runs a script to output the Network Adapter Utilization. The name of the datasource is “Microsoft.Windows.Server.2008.NetworkAdapter.BandwidthUsed.ModuleType”. This datasource module uses the timed script property bag provider, along with a generic mapper condition detection. The script name is: “Microsoft.Windows.Server.NetwokAdapter.BandwidthUsed.ModuleType.vbs”

There are 3 rules, and 3 monitors for each OS (2003 and 2008), which utilize this datasource:
  • Rules:
    • Microsoft.Windows.Server.2008.NetworkAdapter.PercentBandwidthUsedReads.Collection (Percent Bandwidth Used Read)
    • Microsoft.Windows.Server.2008.NetworkAdapter.PercentBandwidthUsedWrites.Collection (Percent Bandwidth Used Write)
    • Microsoft.Windows.Server.2008.NetworkAdapter.PercentBandwidthUsedTotal.Collection (Percent Bandwidth Used Total)
    • Microsoft.Windows.Server.2003.NetworkAdapter.PercentBandwidthUsedReads.Collection (Percent Bandwidth Used Read)
    • Microsoft.Windows.Server.2003.NetworkAdapter.PercentBandwidthUsedWrites.Collection (Percent Bandwidth Used Write)
    • Microsoft.Windows.Server.2003.NetworkAdapter.PercentBandwidthUsedTotal.Collection (Percent Bandwidth Used Total)
  • Monitors:
    • Microsoft.Windows.Server.2008.NetworkAdapter.PercentBandwidthUsedReads (Percent Bandwidth Used Read)
    • Microsoft.Windows.Server.2008.NetworkAdapter.PercentBandwidthUsedWrites (Percent Bandwidth Used Write)
    • Microsoft.Windows.Server.2008.NetworkAdapter.PercentBandwidthUsedTotal (Percent Bandwidth Used Total)
    • Microsoft.Windows.Server.2003.NetworkAdapter.PercentBandwidthUsedReads (Percent Bandwidth Used Read)
    • Microsoft.Windows.Server.2003.NetworkAdapter.PercentBandwidthUsedWrites (Percent Bandwidth Used Write)
    • Microsoft.Windows.Server.2003.NetworkAdapter.PercentBandwidthUsedTotal (Percent Bandwidth Used Total)

Only the “Total” rules and monitors are enabled by default, the Read/Write workflows are disabled out of the box by design.

The good:

This new functionality is cool because it allows us to monitor the total utilization based on the network bandwidth as a percentage of the “total pipe”, report on this, and view the data in the console:


The issue:

Since there is no direct perfmon data to collect this, the information must be collected via script. I wrote about how to write this yourself HERE.
There are 4 known issues with this script in the current Base OS MP, which can cause problems in some environments:

1. When the script executes – it consumes a high amount of CPU (WMIPrvse.exe process) for a few seconds.
2. The script does not support cookdown, so it runs a cscript.exe process and an instance of the script for EACH and every network adapter in your system (physical or virtual). This makes the CPU consumption even higher, especially for systems with a large number of network adapters (such as Hyper-V servers).
3. The script does not support teamed network adapters very well, as they are manufacturer/driver dependent, and are often missing the WMI classes expected by the script, so you will see errors on each script execution, about “invalid class”
4. On some Windows 2003 servers, people have reported this script eventually causes a fault in netman.dll, and this can subsequently cause some additional services to fault/stop.

From a CPU perspective – below is an example Hyper-V server with multiple NIC’s. I set the rule and monitor which use this script to run every 30 seconds for demonstration purposes (they run every 5 minutes by default).

You can see WMI (and the total CPU) spiking every 30 seconds.
After disabling all the rules and monitors which utilize this data source, we see the following from the same server:

Based on these issues, I’d probably recommend disabling these rules AND monitors for Windows 2003 and Windows 2008. They seem to create a bit more impact than the usefulness of the data they provide.

Kevin Holman

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