Background initialization check the entire disk surfaces of the disk for errors, and will mark the areas for non use if any are found. The dangerous part, if too many errors are found over the entire array, the adapter gives up and fails the entire array... there is no way around background initialization. With older technology adapters, without the equal of patrol reads, (which checks the entire array surface periodically), many errors could build up in unused areas of the disk, causing multiple disk failures, thus array failures occur during rebuild. Basically, unless an equal of patrol reads is running, the danger of multiple disk failures is high during background initialization...the larger the capacity of the array, the higher the risk. 

Initialization on the other hand is much like a format, completely wiping your data and checking the array surface. No matter what happens with an array, even with an array failure, you do not want to consider this if you have data to recover.

Lastly, reseat the adapter /all cables , get your firmware up to date. If the disk go offline again, you likely have (a) disks which are (going) bad or have a disk firmware bug, the bad boy(s) disks may not be the disks which offline.

Thanks for your reply! After doing a full backup I allowed the Background Initialization to complete and everything was left intact.

Thanks,

Charles Haven