I tried creating a 8TB volume (24TB disk space) following the instructions in this video:
https://www.youtube.com/watch?v=YCMig-zEBKU
Everything was find until I hit create. SoftRAID threw an error (I can't recall what exactly because it went away) so I'm trying to re-initialize, delete, anything to recover the 8TB of disk space so I can try again (certify showed both disks good after 5 days of checking). Because Safeguard is enabled, I can't do anything. Expected...except I can't disable Safeguard. The option is there, but nothing happens. It asks me for my admin password, but then does nothing.
Now what?
(Screen capture attached)
I suspect you do not have Secure Boot disabled, or the driver is not loaded. If oyu have a T2 chip, follow this:
https://srforums.wpengine.com/pages/support/faq/faq_imacpro_secureboot.html
Then run this command in terminal to check if the driver is loading:
sudo kextstat -b com.softraid.driver.SoftRAID
If the result is blank (not listing 5.8.3), follow these to make sure you have the driver unblocked.
https://srforums.wpengine.com/pages/support/5.8_Volumes_Not_Mounting.pdf
I'm using High Sierra on a 2012 iMac. I don't think I have the T2 chip in my machine.
I ran the code in terminal and it showed me nothing.
I didn't update...I installed 5.8.3 directly.
Disconnect your drives.
"uninstall SoftRAID" from utilities menu.
Then go through these steps:
(Some are not for High Sierra, don't worry about those)
Worked....thanks!

