Creating another raid array after creating a raid and install os on it

Hi all,

I want to create another raid array on existing server. I have previously 8 x 2 TB hard drives as raid 10 and i have installed esxi on it and using as a backup for all other esxi on our data centre.

But I'm getting low on storage and i want to increase it as there are 4 drives more can be put there.

As it is a critical situation and i can not loose data so is it posaible that i put more drives and create a second raid array ?

so i can move something on that. will this effect my main raid array ?

Server: Dell r730 xd

1 GB raid card