Expand LSI RAID using StorCli

So I purchased 11 x 6TB HDDs the other day but the reseller didn't have enough on stock. We were running out of space and I asked them just ship 7 HDDs for me to build the raid 6, I can add the other 4 in later.
With 7 HDDs, I can build 30TB volume, that will be enough for us while waiting for the rest turning up.

here is the command that I used to add 4 HDDs to existing RAID 6 volume:

storcli64 /c0/v2 start migrate type=raid6 option=add drives=9:1,2,3,4  

c0: Raid Controller number

v2: Virtual Disk

type: we keep the raid level ( 6)

You can check status by running
storcli64 /c0/v2 show migrate It will take few days to migrate and re-calculate all the parity on the RAID.

VD Operation Status :  

VD Operation Progress% Status      Estimated Time Left  
 2 Migrate           0 In progress 5 Days 4 Hours 39 Minutes