Beta 6 Disappearing RAID???

I have the same problem with my Areca 8050 TB Drive on my Mac Pro 2013. If i plug it into my MacBook Pro 2016 with Apple TB 2/3 Adapter the Disk mounts fine. On my Macbook is an older Beta from Big Sure. I created a Feedback in the Feedback Assistent App.

ARECA thunderbolt RAID devices do not work with Big Sur public Beta. Areca are aware of the issue but do not provide a solution.
If you are stuck with not being able to access your data after installing the beta you can do the following

Using Areca RAID on Big Sur Beta

Copy ArcMSR.kext from /System/Library/Extensions to /Library/Extensions

You can now manually launch the RAID support by typing the following command in a terminal window

Code Block 
sudo kextload /Library/Extensions/ArcMSR 

The RAID will show up in finder

The support will be lost on each reboot.


To automate the process

To automate the process on bootup a few things need to be done

1 - Enable sudo support for the required commands without password

open a terminal

type

Code Block 
sudo visudo /etc/sudoers

use the arrow keys to scroll down to place the cursor on the line directly below the section

Code Block 
# User privilege specification
root  ALL=(ALL) ALL
%admin ALL=(ALL) ALL

Type i to enter insert mode


Type 

Code Block 
ALL username = NOPASSWD: /sbin/kextstat, /sbin/kextload

(note usernameshould be your username as shown at the start of the prompt line in the terminal)
hit return key

Type :wq hit return key

The sudoer file is now updated to permit execution of the two needed kext commands without entering a password

2 - write a script to run the required commands

launch Script Editor. The easiest way is to use cmd space and start typing Script Editor in Spotligh Search

Create a new file and type the following

Code Block 
try
do shell script "sudo kextstat | grep \"com.Areca.ArcMSR\""
on error
do shell script "sudo kextload -v /Library/Extensions/ArcMSR.kext"
end try

Save the file to a suitable folder. I used my home folder. I called the file areca_kext.scpt

You can test the script by running it from within the Script Editor. You can tell if it works as the RAID will become visible on your system. You can also use a terminal and run the command

Code Block 
sudo kextstat | grep “com.Areca.ArcMSR”

If the script worked the command will show the ArcMSR kext as being loaded.

3 - Create a launch Daemon to automatically run the script

Using a text editor create a file ~/Library/LaunchAgents/com.areca.kext.plist

(note: This makes support available for the logged in user only. To have support for all users place the plist file in the /Library/LaunchDaemons folder instead. I have not tried this approach)

add the following text to the new plist file

Code Block 
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
    <key>Label</key>
    <string>com.areca.kext</string>
  	<key>ProgramArguments</key> 
  	<array> 
  		<string>/usr/bin/osascript</string> 
    	<string>/Users/username/areca_kext.scpt</string> 
  	</array> 
  	<key>RunAtLoad</key>
    <true/>
</dict> 
</plist> 

The Label attribute should be the same as the Deamon file name and the second string in the ProgramArguments array needs to be the script file you created in step 2

Reboot your computer and the RAID should be mounted when you log in.

Once support is provided directly by Areca and Apple simply remove the plist file and normal service will be resumed.

Hope this helps out some other early adopter who wasn't aware there was an issue...