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The VMware Flings website is a well-known resource site from VMware that hosts new tools, projects, and ideas. Some of these tools and ideas are so good that they have been integrated as features or functions into VMware products. VMware DRS Dump Insight is one of them.
DRS Dump Insight analyzes the log file data from your DRS cluster. You can get answers to questions like why your cluster is not balanced, or check what-if scenarios to see what happens when you change some advanced configuration within your DRS.
The output is a series of visuals where you can see what moves DRS has made. It is a SaaS utility where you upload your DRS dump files, which were previously created on your vCenter Server.
As you know, VMware Distributed Resource Scheduler (DRS) enhances the workload balance of your VMs in a vSphere cluster managed by vCenter Server.
The DRS dump utility is compatible with the latest vSphere 7 and is backward compatible with vSphere 6.x as well.
How do I use DRS Dump Insight? ^
It's fairly simple. I assume that you are running vCenter Server 7.
To use DRS Dump Insight, upload the drmdump log files, which are found on your vCenter Server, to the web app at https://www.drsdumpinsight.vmware.com/.
Once you connect to the URL, you're redirected to this page, where you simply accept the technical preview license and choose the folder where the dumps reside. The folder must contain unzipped dump files. You can find the drmdump files in the vCenter Server appliance in the following folder:
To find the domain ID, click the cluster in the vCenter Server UI and locate the [domain-ID] in the URL from the browser.
When you hover your cursor over the Choose Folder text, a tooltip explains you must limit the number of dumps in the folder you'll be uploading to a maximum of 100. This limit basically means you'll avoid high waiting time during the dump analysis.
You can see the UI in the screenshot below.
Do a what-if analysis on your cluster ^
Users can use the utility portal to upload their DRS dump files, sort out when they want to change their DRS migration threshold, or decide when to delete their affinity or anti-affinity rules.
The tool option enables performing an analysis of changes to DRS advanced options and doing a what-if analysis if DRS options are changed.
As you can see, the results are quite interesting, giving you an idea of what can happen if you change this or that advanced option within your DRS cluster.
Another example from the VMware Fling site is shown below.
DRS dump log file formats ^
With the second release of the utility, the format changed. Each drmdump (Plmt-*.log) file has many dumps, which can be categorized into two main types:
- Partial dumps—These dumps are created whenever a VM is powered on or migrated to another host. This usually happens during load balancing, initial placement, or when an ESXi host enters maintenance mode. Another scenario is when you have affinity and anti-affinity rules enabled and created within your cluster, and the system tries to correct the rule violations.
- Full dumps—These dumps have information about all the active VMs and ESXI hosts present in a cluster and are created every three minutes. So there are a lot of these.
Here is a screenshot from VMware showing some examples from the UI for vSphere 7.
The best way to start using this utility is probably to test it yourself and study the user guide a bit. You can find a PDF version of the user guide here, which has only about 20 pages.
You'll be able to learn what we can cover within this small article. For example, you'll see that the host resource usage before and after the DRS is run can be shown as the percentage used across all cores. You can also see that the memory is shown as the overall percentage used, which gives you an exact view of the resource utilization changes per host during a specific DRS run. There are also many screenshots in the PDF that show you some tips on how to make the most of this tool. Here is one of them.
Final words ^
The DRS dump tool enables analyzing your DRS dumps from vSphere 6.x and above. You should use the Chrome browser, as recommended by VMware. There are no other requirements.
The export as PDF feature allows you to export multiple dump analyses as a single PDF file for offline read or archiving. Perhaps some automation magic could be added to vCenter Server, where you would set a date and time at which you'd like to upload your dumps into the utility and predefine the export as PDF as well. Another good option would be getting the exported file delivered to your mailbox each week or month.
I think this utility is pretty useful for admins who want to have a clearer picture of how their DRS is handling their vSphere environment, as these details might simply fly under the radar under normal circumstances.