There have been many blog posts and some really good EMC whitepapers describing what goes on under the covers of a Storage Pool-- so I won't go into detail on that.

But here is a list of the different kinds of "private RAID groups" that are created as part of a storage pool "behind the scenes" depending on the number of similar drives within the pool".
<div>RAID 5</div>
<div>
<ul>
	<li>2+1 (3 disks)</li>
	<li>3+1 (4 disks)</li>
	<li>4+1 (5 disks) ** RECOMMENDED</li>
	<li>5+1 (6 disks)</li>
	<li>6+1 (7 disks)</li>
</ul>
<div>RAID 6</div>
<div>
<ul>
	<li>2+2 (4 disks)</li>
	<li>4+2 (6 disks)</li>
	<li>6+2 (8 disks) ** RECOMMENDED</li>
	<li>8+2 (10 disks)</li>
</ul>
<div>RAID 1/0</div>
<div>
<ul>
	<li>1+1 (2 disks)</li>
	<li>2+2 (4 disks)</li>
	<li>3+3 (6 disks)</li>
	<li>4+4 (8 disks)</li>
</ul>
</div>
</div>
</div>