I think that depends on what OS he is running.
On the newer OS, as long as there are at least 2 drives of the larger size, no space will be wasted. You can mix 9G and 18G in the same vol.
"Mohler, Jeff" wrote:
Sure, no problem.
But when you add them to a volume (if you are not creating a new one) make sure you add them to the volume made up of 18G drives. (That is, if the 18G drives are a separate volume from the 9G ones).
If you mix/max drive sizes in a volume, the larger drives will appear only to be the size of the smallest drive in the array.