I have a 4TB RAID10 array on a Perc 5/i. I am running out of storage. On the 5/i I cant expand a RAID10 so the only option would be to buy 2 extra hard drives and rebuild an 8 drive array.
Though I did come up with an other option. Make another RAID10 and run LVM across the two. Thinking about this it could potential be more redundant. If I do loose 2 adjacent disks on one of them then I only loose half the LVM and could potentially recover the other half. The only disadvantage I can see is that you would get a read speed increase.