Is your RAID or Server missing partitions? The main reason why partitions go missing on a RAID is due to file system corruption.
Think of the file system like an index of a book. How the index of a book tells us where data is stored within the book, the file system does the same in hard drives.
IF the file system gets corrupts, files and folders OR partitions go completely missing. Our equipment will allow us to image/clone the entire drive, then run a scan on all of the sectors and rebuild the original file system.
Please don’t attempt to repair the file system using Disk Aid, Disk Check or other file system repair tools as this will make the situation worse.