Hi!
I´m planning the upgrade from our current version of Splunk (V 6.*) to 8.1.3 on Server2016-19 and to V 7.3.9 on Server2012
Do anyone knows if a reboot of the computer should be needed?
Can I install the new version directly without unistall the previous one? It´s needed to backup/restore any file to maintan the current configuration after the upgrade?
Typically, installing Splunk does not require rebooting the server, even on Windows.
Also, typical, one can install Splunk over an existing installation. It's a good idea to back up $SPLUNK_HOME\etc before the upgrade.
That said, yours is not a typical upgrade because it spans two major versions. It's made more challenging by the lack of release notes for the several unsupported versions you're skipping. I just contacting Splunk Support to see if they can send you links to the release notes for those versions so you know if there are any special steps required for that version.