Yes, Splunk can be installed on your internal servers, even on desktops/laptops.
- online servers (splunk cloud) is only for some other specific requirements(internal servers not available, just for a Proof of a Concept project, festive sessions load mgmt, etc).
Yes, you absolutely can install Splunk on your own servers and store your data there. That's the original way Splunk worked and it is still very common. Just go so splunk.com and click the "Free Splunk" button to begin. Depending on the amount of data you wish to store, you may need to install Splunk on multiple servers.
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