Perry Whittle (7/29/2013)
Even using a partitioning tool on an online cluster volume, i'm not sure this would be a wise thing to do, i assume this is what you are using.IMHO, It's far easier and less work to create 2 new LUNs present them and set them up and move the datafiles as required.
True.
But the problem is that there is no additional space or disks on the SAN. That's the whole point of doing this, re-use the existing LUN and divide it in two. If we have space, we would not be worrying about re-purposing that existing LUN.
Doing it offline it's actually easy, as that LUN only contains tempdb files, but we need the whole downtime window for the migration project. If I had enough time, it's just destroying the LUN (after taking SQL off and probably removing the disk resource from the SQL failover package) and create two new volumes inside.
What I am using is Disk Management tooL, from Windows. It is pretty simple. Right click, shrink, and select the new size or value. It can be done with diskpart as well but it is easier with the GUI.