Very rarely, the ArcSAS driver can become stuck; Functioning improperly, un-removable, un-updatable. This is not a common problem, but if you have exhausted all other solutions, it may solve your problem.
To diagnose if this may be the case, start by typing in the following into the Terminal.
ls -l /Library/Extensions/ArcSAS.kext
This command will help identify if the file in question exists. If it returns "no such file or directory", this will not solve your problem. You may need to ensure the driver was properly installed
If the driver does exist, but the MagStor is not functioning, the following solution may solve your problem.
Proceed with caution
The following solution is dangerous as a typo could lead to the deletion of important files. It uses root access to remove the file in question. MagStor is not liable. You run this command at your own risk. For your safety, triple check you have it right.
sudo rm -rf /Library/Extensions/ArcSAS.
You will be prompted to type the root password. You will not see the password as you type it. Once the password is entered, hit enter.
Now when you run.
ls -l /Library/Extensions/ArcSAS.kext
You should see "no such file or directory". Reinstall the driver and your problem should be solved.