Legacy Extension Warning Popup Procedure Question

No, that’s not the current procedure. I’d start looking for a modern replacement for that software (and perhaps hardware).

The procedure to run legacy kexts is to boot into Recovery, put your Mac in Reduced Security mode, snd there is a tick box to allow legacy kernel extensions. Personally, I would not run my Macs with Reduced Security.

I’d interpret that vendor message as indicating the vendor has an update available which deals with this automatically, so dismiss the message, update the app, and subsequent restarts will not get this message.

If that LaCie update doesn’t work, I’d next try a Safe Mode start, and then restart normally. This to clear the caches.

Then failing that, see if the vendor has a documented app removal procedure for your particular LaCie RAID storage gear, follow it, and then re-install the current version of the app.

It is possible to go spelunking too, but I’d rather not start there.

No, I saw it. But you can't really turn a kext file off. They must be removed to prevent them from loading. As proven by the fact the OS keeps asking you to do the same thing.

Look in this folder:

/Library/Extensions

The only two files in there by default are:

HighPointIOP.kext

HighPointRR.kext

Anything else was added by third party software.

You should never need any sort of software to use a drive. My guess it is some garbage where they bundle with the drive that you don’t actually need and should probably just uninstall it instead of reducing security.

I would double check what they're for before canning them, just in case other 3rd party software put something there it relies on. Other than what was installed from the apps that came with the external drives, that is.

For instance, if you use Toast Titanium, it always installs the Soundflower kext. An open-source extension known to be poorly written.

If you know for certain a kext file can be removed, put it in the trash. You'll be required to enter your admin password to complete the move. Been a while since I deleted Soundflower, so I can't remember if you have to restart the Mac before you can empty the trash. A restart will also take longer when you remove a kext file as the OS does whatever to unregister the kext during the startup sequence.

There are no "features" any of the junk software included with third party drives that are even slightly helpful. They only succeed in adding complexity to read/write operations. The OS does not need any help handling its own functions. Remove all such third party software.

For any unknown kext files you may find in that folder, just copy the full name and do a web search of it. You can almost always find out what app installed it.