Humphs,   A foreign drive doesn't happen due to a drive failure, but instead is caused by the Virtual Disk configuration information is different between the drive and the controllers. The controller and drives both contain information regarding the Virtual Disk configuration and one of those has changed. Now with clearing, you are telling the controller to Clear the VD config information from the drive and go with the controllers config information. Importing the foreign is doing the opposite, it is telling the controller to use the drives VD config information instead of its own. Now normally the rule of thumb is if the VD is still booting then you would clear the foreign, because if it is booting the information used is correct. If the VD isn't booting then the config data isn't correct on the controller and you would need to import the drives config information. Now with either of these it doesn't effect the data, just the configuration information. Now if these fail then you can still try retagging the VD which is deleting the VD then recreating it exactly the same without initializing the VD (which would delete the data), doing this will replace the VD configuration information on both controller and drives.   Let me know if this helps.    
I have a server in a remote location and one of the physical disks is showing a foreign state. Maybe it's defective or beginning to fail? I don't know. I'd like to attempt to get it back online by using the Clear function in the Foreign Configuration section. I just want to make absolutely clear that I'm not to going completely the system. lol Especially when it says that it will "remove metadata associated with the virtual disks, making the physical disk drives available for creating new virtual disks". I just want to make sure that this function is only going to affect the one, foreign disk that I'm having a problem with. I have some screenshots below. Cheers!  [IMAGE][IMAGE]      
Clearing foreign state