Troubleshooting Performance Issues in VMware with vscsiStats

If you are running VMware ESXi and want to verify the performance of your virtual machines (VMs), one tool you can use is vscsiStats. This command-line tool can help you determine if there is any significant latency in your storage environment. In this blog post, we will discuss how to use vscsiStats to troubleshoot performance issues.

1. First, find the world ID of the VM you want to monitor the performance of by using the following command:

# vscsiStats -l

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2. Once you have the world ID, you can start monitoring the VM’s performance using the following command:

# vscsiStats -s -t -w <worldID>

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3. After a few minutes, you can check if any data is being collected by using the following command:

# vscsiStats -p all -w <worldID>

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4. If you want to save the data in a CSV file to import it into Excel, use the following command:

# vscsiStats -p all -c -w <worldID> > /tmp/vmstats-<vmname>.csv

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5. When you are finished monitoring, stop vscsiStats using the following command:

# vscsiStats -x -w <worldID>

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Using vscsiStats, you can create diagrams that show the latency of your storage environment. This can be particularly useful in NFS environments, as esxtop does not show this information.

If you want to learn more about vscsiStats, you can check out this article by Gabe Van Zanten, which provides more detail on how to use the tool. Also check out an article from Duncan Epping. You also can use vscsiGrapher from virten.net

In conclusion, vscsiStats can be a powerful tool for troubleshooting performance issues in your VMware environment. By monitoring the performance of your VMs using vscsiStats, you can identify any latency issues and take steps to improve the performance of your storage environment.