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  • 1.  Performance Debugging and Get-Stat Efficiency

    Posted Jun 12, 2017 03:05 AM

    Hello all. First-time poster here.

    I've recently been working on some stuff to gather performance metrics with Get-Stat in a daily report that appends daily data to monthly CSVs, which is later turned into monthly reports with Google Visualization / Google Charts API.

    Just gathering datastore metrics alone my script takes a good 30-35 minutes to run currently.

    I am not doing a TON of looping, as I'm doing some things like.

    $datastores == Get-Datastore

    So as not to loop through with a lot of calls to VI Server.

    However I am doing loop over the $datastores and then running two Get-Stat in there. There's a total datastores of 138 in this environment. Though I am also running a storage consolidation project that will reduce this drastically in the future... that's what, 272 Get-Stat calls?

    I wonder if I should just do something like

    $stats = $datastores | Get-Stat -Stat "blah"

    And look at the data within a loop.

    Thoughts?

    Any other efficiency tips or recommendations would be great too.

    I've not been using Powershell / PowerCLI long if you can't tell.

    Perhaps another good question would be how you might debug PowerCLI performance issues? Maybe with the Windows PS ICE? I think you can set breakpoints.



  • 2.  RE: Performance Debugging and Get-Stat Efficiency
    Best Answer

    Posted Jun 12, 2017 04:45 AM

    Yes, you are correct.

    For performance reasons try to limit the number of Get-Stat calls, these are quite expensive regarding execution times.

    The Group-Object cmdlet is a big friend for that.

    Have a look at my PowerCLI Performance Statistics posts.

    These contain a number of basic concepts and techniques for retrieving vSphere performance statistics.

    For debugging PowerShell/PowerCLI scripts you have multiple techniques at your disposal.

    The breakpoints in the ISE are one way, but there are other helpful tools for debugging your scripts

    • using the Write-Verbose and/or Write-Debug cmdlets
    • using transcripts with Start- and Stop-Transcript

    If you want to invest (they cost $$), there are some tools, like ISESteroids, that offer more features than the ISE.

    And last, but not least, the free Visual Studio Code editor with the PowerShell extension, is nowadays at least up to par with the ISE.

    And more and more features keep being added.