I Think this is wrong?

I suspect that it is configured in a RAID 1 and that a disk failed and someone tried to replace the failed SAS disk with a SATA disk.  Because you can't mix SAS/SATA in a virtual disk, it would have just sat there in a "ready" state.  If this is the case, your data is in great danger, as the only remaining disk is showing predicted failure and could fail at any time.

Go to the Virtual Disk screen ... what does it show?  If you don't have a backup, get one now.

Is there a method of determining if it is set with RAID 1? I fear that RAID has not been configured and the second disk is just being used to extend the the overall size.  It does report Disk 1 is 931GB and the 2nd disk is only 698GB.   Would I not be able to purchase another SAS disk and slot in so the RAID would build? 

You are right about the SATA, there is a SATA disk sitting in the server. Doing nothing and not even active within Windows.  

So the 2nd disk according to Windows is doing nothing. 

Hi, 

Yeah I completely agree with everything you are saying. I have also found out that the guy before did set up the RAID but ordered the wrong disks, (We can see that) However I have just been handed a 1TB Sata disk and asked if we can mirror the SAS disk to this, then remove the SAS disk and order a 2nd SATA disk to then use in the RAID. 

I am not sure this can be done due to drivers for each of the disks in the Windows boot files. Is it even possible to go from SAS to SATA just by cloning the disk and adding drivers? Surly I would need to rebuild the whole OS? 

I see the easy options are to either order 2 new SAS Disk. Insert 1, Build RAID, Remove old one, Rebuild RAID. Or get a new server as this one is old!!! If I did order a new SAS disk, would it have to be exactly the same as the existing one?

According to your second screenshot it IS RAID 1 and further validates my original assumption. The disk woul not have rebuilt if smaller than the original or a different type (SAS/SATA). If Windows does see the SATA disk, you are using a RAID controller that does not support non-RAID, so an individual disk cannot be used outside of a RAID array. Get a SAS disk 1TB or larger, and it should rebuild.

You can clone the data from one to the other, but you can't simply "mirror" them as they are.

Option 1 (best)

Get two SAS disks, rebuild SAS disk into RAID 1, remove failing SAS disk, insert second new SAS disk, rebuild RAID 1.

Option 2 (next best)

Configure SATA disk as a 1-disk RAID 0, image data from SAS RAID to SATA RAID, remove SAS disk, delete RAID 1, add second SATA disk, reconfigure 1-disk RAID 0 to 2-disk RAID 1.

Option 3 (bad)

Configure SATA disk as 1-disk RAID 1, use Windows Disk Management to mirror disk 0 to disk 1.

Which controller do you have?