I would back up any important data before doing anything else. RAID is not a backup solution and you should back up everything on there that you want to keep.
In the Adaptec Storage Manager you can add another drive to the array and it will rebuild itself, which spreads your array data across four drives instead of the 3 current drives. There are instructions in the ASM guide, but basically you just select the array in ASM then select the logical drive, select actions in the menu bar and pick Expand or change logical device -- it will open a wizard that will guide you through the process.
thanks realbeast, I have the data backed up. I have successfully added the fourth drive in ASM but I did not create any logical drives when I first set it up. In disk management of WHS 2011, it shows the drive size as 3.6 TB, the same size as when I had 3 drives Hooked up.
If all I have to do is wipe the disk and start over by creating logical drives, I will. I just didn't want to do that to find out that wasn't the problem.
You can probably add the drive under WHS 2011, but I would probably go ahead and build a new RAID 5 array using ASM. If you ever have a RAID controller failure you could put the drives on a new Adaptec controller and rebuild, which you cannot do in your current configuration.
Thanks, I was trying to avoid that, but think you're right. This is my first foray into RAID 5. I have been running RAID 0 and 1 boxes for years without indecent. They run so smooth that I forget they are there.
I still can't wrap my head around the logical drive part of this. WHS saw my Phisical drive that ASM showed it and I partitioned drives from that in Disk management. Why do I need Logical drives?