If you are trying to expend a raidset on a system with HP storage controllers you can use this.
Please note: you need to have a BBWC if you want to expand an array.
First check if the disks you added are detected:
hpacucli ctrl all config show
If you see the disks at the unassigned section we are good to go.
hpacucli ctrl slot=0 array A add drives=allunassigned
Get the slot and array information from the first output.
The expansion can take up allot of time. This is al depending on disk size and performance.
If the first process is done we need to set the logical disk to max space.
hpacucli ctrl slot=0 ld 1 modify size=max
If this is all done you probably need to expend your partition as well.
I would say, google is your friend!