Sadly the wording is somewhat misleading. Using CPUSE/Blink, the "clean install" option doesn't mean anything other than the running Gaia configuration getting wiped. You are not doing a "clean install", per se. The only way to get a proper clean install is by using ISO/USB/LOM.
The only way to get the new XFS filesystem is by doing a proper clean installation using ISO/USB/LOM. This is the only way to get the 4k alignment introduced with R81.20 as well. Things such as the new default for most deployments being user-space firewall, not kernel-mode firewall is not being changed when doing CPUSE/Blink installations either. You have to do a proper clean installation or make the change from KMFW to USFW manually afterwards. Things like NIC firmware upgrades do not seem to happen unless you do a proper clean installation either. The amount of things requiring a proper clean installation is starting to add up. I'm striving to do proper clean installations using ISO/USB/LOM every time I move from one major version to another.
I don't think Check Point is doing a very good job detailing what you are missing when upgrading compared to a proper clean installation. It would be beneficial for the R81.20 upgrade and installation guide to detail everything you will miss by not doing a proper clean installation.
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